He was in a play, and when he finished acting he asked his wife how he did, and she said something along the lines of "you did really great, and no one even noticed when you messed up your lines".
That sent him into a fit of rage and he kicked her to death.
Caligula was nuts. he'd sleep with other dudes' wives and then laugh in their face about it, randomly pick sections of the crowds in the coliseum to be fed to the beasts during intermission, slept with his sisters and prostituted them out, appointed a horse as his consul and a priest, basically let Rome starve, had massive orgies in the palace, one of which lasted like 80 days, tried to build a statue of himself to be worshiped in Jerusalem, and tried to build a floating bridge just so he could ride around on it.
Oh, he also made it a crime to mention a goat around him, punishable by death and replaced a bunch of the heads on statues of gods/demi-gods with his own.
He did all of this in 4 years before he was assassinated.
Ironically the senate tried to save Nero because he was the last of the bloodline and they wanted an heir instead of having to pick out a new emperor... but Nero had his servant kill him before he knew of the senates plans.
How fucked up is THAT!? LOL
This isn't even close to the craziest/most messed up things he did though. He slaughtered tens of thousands of christians in the coliseum either through crucifying them or feeding them to animals, had some covered in oil and set fire to illuminate his courtyard, had his mother executed, supposedly caused the great fire of Rome, and sat idly by as it ravaged the city.
That sent him into a fit of rage and he kicked her to death.
Oh, he also made it a crime to mention a goat around him, punishable by death and replaced a bunch of the heads on statues of gods/demi-gods with his own.
He did all of this in 4 years before he was assassinated.
How fucked up is THAT!? LOL