During the thirty years they were separated, neither Jerk Ford nor Stanley celebrated their shared birthday.
They did however, form the same yearly tradition simultaneously, and completely independent of one another. Showcasing how they manage to mirror each other even when their twinstinct was gone.
While Stan is well liked, he didn't have to worry about anyone trying to do a surprise party for him. Most of his peers are teachers who wouldn't work at the school during the summer unless if they were staffed for Summer School that year. His part time job during summers is working at the Water Treatment Plant, but he always kept a low profile that day and made sure none of his coworkers knew his birth date.
Even when he adopted Soos, Abuelita respected that Stan did not want to celebrate his birthday, because she knew the reason why he didn't. And considering Soos still hates his own birthday just like in canon, Soos wouldn't question his dads lack of birthday celebration.
Jerk Ford is out in the multiverse, and not celebrating birthdays is common in the Fordverse. Most of them resent (but 'secretly' painfully miss) their twin, and the most common goals out in the multiverse are survival and killing Bill Cipher. Jerk Ford's lack of resentment towards his brother is not well known, so him also not celebrating is no surprise.
Even as he starts to steadily gain more friends allies during his thirty year exile, he maintained his refusal to celebrate the occasion, and most likely kept to himself that day. Which they do not question; Anti-Ford and Watchdog Ford have the same birthday and could understand why, meanwhile The Archivist is a few centuries old so birthdays don't have as much meaning to him compared to a regular human or shorter lived species.
But what same yearly tradition do Jerk Ford and Stan do in place of an actual celebration or event? Well...
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Dimension-???
Unknown bunker, unknown city. 15 June 2011
Jerk Ford makes sure he's absolutely as secure and far away from others as possible; there's statistically a very low chance of anyone finding him anytime soon, but just in case he has a syringe of his patented Drunk-B-Gone with a capped needle readily in his right overcoat pocket.
He reaches into his extradimensional bag and pulls out two items - a snifter glass, and a dark bottle of Seagrams Seven Crown.
He'd remembers back in their Backupsmore days, he and Fiddleford used to tease Stanley about his so-called 'sophisticated' taste, how he wasn't more manly than them just because he kept his drinking habits on the plain and simple side, but Stan would continue to insist he wasn't trying to make a statement, he just preferred it that way.
Sometimes Jerk Ford wondered if Stan was emulating their Pa or if it was just coincidence and genetics they both happened to prefer whisky and refused mixed drinks of any kind. Laphroaig was Filbrick's poison of choice, and just like Stanley he only ever drank things as they were, nothing 'fancy' like simply syrup, a lemon garnish, or God forbid, ice.
Jerk Ford, for one, preferred not consuming the equivalent of potable acetone, but...
"At least I didn't have to try to smuggle ice or citrus fruit." Jerk Ford mused out loud to himself as he poured from the bottle into the glass what he eyeballed as 4.5oz of whisky, the equivalent of three shots.
Fine whisky is supposed to be drunk in small sips, but Seven Crown is cheap and bottom shelf, it could be knocked back, and that's what Jerk Ford was planning on. He knew it wasn't the wisest thing to do, he wasn't unaware of his steadily declining constitution. It was the same reason he generally didn't drink anything bigger or stronger than a singular beer even when going out to drink.
"Happy Birthday, Stanley." Jerk Ford murmured to himself before swigging the whole thing down even though he hated it.
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Dimension-PJC311
Gravity Falls, Oregon. 15 June 2011
Stanley Pines walks into Skull Fracture, the toughest bar in town- mainly because it was the only bar in town. The heavily tatooed biker serving as the bouncer tended to roll his eyes whenever Stan came to the bar, because of how much a school teacher like himself stood out amongst these self-proclaimed extremely tough people and bikers, but this time he just nodded at Stan and allowed him inside with no words.
29 years of this, Tats had of course expected him.
However, it appears tonight there was a different bartender than normal, or at least one Stan didn't usually see. A large biker with a bald head, and a red bandanna tied around his forehead like a headband.
"Mr. Pines?" The bartender asked in surprise "Monthly Cigar Night isn't until-"
"I know, I just need a drink." Stan interrupted him as he pulled out a stool in front of the counter and promptly sat down.
"The usual?" The bartender asked, already reaching for a Glencairn glass from the cabinet, but Stan raised one hand in the 'pause' motion.
"A mixed drink." Stan explained, internally rolling his. The establishment and its usual patrons prided themselves in their toughness so much, they refused to have cocktails because 'those are girly drinks'.
However, there was an easy work around; just call it a mixed drink and explain exactly what you'd like in it. A person can't ask for a Rusty Nail cocktail, but they can ask for a mixed drink equal parts scotch and Drambuie, served on the rocks in an old fashioned glass.
"What do you want in your drink?" The bartender asked him, and Stan recited it from memory
"Equal parts vodka, tequila, white rum, triple sec, gin, two parts lemon juice, one and a one-third parts simple syrup, and top it with cola. On the rocks, and in a highball glass, please." Stan instructed carefully, and the bartender nodded along as he put said drink together.
"You sure about this, Mr. Pines? This is five shots." The bartender pointed out, but Stan simply shrugged, and switched a ten dollar bill with the bartender for the drink.
Stan for one, didn't like most cocktails. He liked sweets just fine, but he always preferred things with a robust, earthier taste, and overly sweet things gives him headaches. But his long lost twin brother, Stanford? A sugar fiend.
In the early years of their adulthood, he used to pick on Ford about how he might as well just drink club soda and simple syrup, with the types of cocktails he'd usually order.
It made Stanley wonder how similar Ford really was to their Ma, considering that the glass of wine she had with all three meals of the day were typically dessert wines. Stan personally didn't know if she ever drank anything harder when she wasn't around her children, but he did know her favourite was Graham's Six Grapes.
Long Island Ice Tea was one of the most basic bitch cocktails someone could get. And for some reason, it was the one Ford ordered the most frequently.
Drinks served with ice should be drunk quickly, because of the ice melting, diluting the drink and the taste. But Soos, alongside his fiancée Melody, were currently chaperoning Wendy and her friend groups camping trip near Lake Gravity Falls.
Meaning his home was currently empty. Like many nights before Soos, it was just Stan alone with the non-functioning portal that had taken his brother away all of those years ago.
He could nurse this drink for a bit, just to give himself a little bit of time and distance from the source of his despair, which also served as his only hope for the future.
"Happy Birthday, Stanford." Stan said quietly to himself when he was sure the bartender and any other patrons were far enough away no one could hear him. And then took his first sip for the night.