Last night, my party managed to roll three fucking nat 1s in a row.
The party separated in a dungeon (bold move, but ok) and two of them were faced with a couple low-level thugs. Even for two characters, these bandits should have been the easiest fucking thing in the world. They should have been able to sneeze and and take them both out with instant onset scarlet fever or sneak up behind them and say "boo" and give them heart attacks. These fuckers had, like, twelve hit points.
And yet... no one was able to roll above an eight for multiple rounds. The thugs were rolling horribly too.
The three nat 1s happened in a row. The paladin swung his longsword and got stuck in the wall. The wizard hurled a bolt of fireball at the paladin, and this encounter would have killed him if I didn't let the wizard reroll getting max damage. And then the paladin ripped his sword out of the wall and promptly dropped it straight through his foot.
I'm imagining these low-level bandit thugs, positioned as watch on yet another boring day to pay the bills, and then spending more than a full round watching the intruders beat the fuck out of each other.
Had the opponents not been so low level, I probably would have just let this 0.0125 percent chance event fucking kill the players.
The roll that finally broke the streak was a 3.