Specifically his right eye, so it's safe to assume that Tim has also clocked the scene unfolding at coat check, where Bernard's date has just arrived.
If his left eye were twitching, it would mean that he hasn't slept in a few days, or has had too many stimulants, or spent too many hours looking at a screen or reading case files in an effort to brute force his way into a breakthrough.
"Bernard," he growls through gritted teeth, fist clenched on his wine glass so tightly that Bernard thinks he might actually hear the thin vessel singing a death scream.
But Tim's right eye is twitching, which means that he is hanging on to his self-control and/or civilian identity — the bland, brilliant, bisexual-and-literally-nothing-else-of-interest CEO of Wayne Enterprises — by the finest of threads, and is genuinely considering whether it would be worth it to do something inadvisable.
In this case, Bernard suspects that the 'something inadvisable' Tim's genuinely considering is storming across this ballroom to bend Conner "aw-shucks" Kent over the coat check counter and rail him until he cries.
Bernard couldn't honestly say he isn't also genuinely considering that himself, so it's not like he could blame Tim for it if he did.
He thinks that would probably be the least surprising development in the situation for the slightly stunned looking coat check clerk who is passing Conner "aw-shucks golly-gosh darn" Kent a numbered ticket in a trembling hand while her eyes dart around in an effort to find somewhere respectable to land. She doesn't have many options.
In all fairness to Tim, his right eye, and the slightly stunned looking coat check clerk, Bernard can admit that it's probably his fault that his date, Conner "aw-shucks golly-gosh darn, here lemme get that door for'ya, ope just gonna squeeeeze past'ya" Kent, just walked into the Wayne Enterprises Holiday Gala wearing an outfit that is only 'a tuxedo' in the most basic sense.
He is indeed wearing the pants and jacket that Tim bought him just last week — accompanied by what they both now understand to have been the unclear advice that, "You can't go wrong with a black tuxedo, so pair this with anything classy under the jacket. If you want to wear makeup or jewelry, just keep it simple, with colors that match your outfit. Don't fret baby, you'll be the best arm candy Bernard could ask for, and you know I'll be watching you all night, too. If you can be good and stick with Bernard for the whole gala, we'll give you a treat once we're back home."
Bernard has a dazed thought that Kon accidentally brought the treat to the gala, and that he and Tim might not be good enough at being good to be tested like this in public.
In all fairness to Kon, he fulfilled the brief to the letter, even if the slightly nervous look on his face as he scans the crowd for them makes it clear that he didn't fully understand the spirit and isn't entirely sure why he's drawing the kind of attention he is in this social environment.
In the right context, brocade is an undeniably classy element of many formal pieces, and there are many in attendance tonight sporting a plunging neckline with copious amounts of cleavage.
His color choices can't be faulted, either, as Kon's far from the only person at the gala wearing primarily black with accents of gold — the hint of gold sparkles on his eyelids are boldly underlined with a gentle smudge of black eyeliner, and he's even wearing the matching set of gold rings and studs in all of his piercings that they just gave him for their anniversary, so his entire outfit is stunningly put-together, in Bernard's opinion.
Really, he would be hard-pressed to name any better, more delicious, more downright fucking edible arm candy in the entire hotel than his half-Kryptonian boyfriend, even if it's making his much more human boyfriend's right eye twitch.
In all fairness to Bernard, when Kon had asked earlier that week about styling a corset, Bernard had assumed it was for the upcoming Burlesque Night at their favorite BDSM club.
everyone should blame and/or thank @opalsong and @tigerlilyandcherryblossom for engaging with me on this post about male corsetry thirst traps, because this is what came of it, despite the very high number of things!!! I still!!! need to do today 😭😭 Why isn't adulting more interesting than sexy fictional boys?