Some games have specific rules and mechanics for characters going insane. Particularly horror based games, such as Call of Cthulhu and others, in which exposure to horrors beyond mortal ken can twist people's minds to the point of breaking. These rules are naturally most often used to track the deteriorating mental stability of PCs - but never forget that NPCs can be seriously unbalanced as well.

Transcript

{Boba takes off with his jetpack}
Boba Fett: {voice over} "They deceived me. They kept this from me. All of them."
Boba Fett: {voice over in flashback panel} "Jango worked for my true father, Darth Maul, who was slain by a Jedi named Obi-Wan Kenobi."
Boba Fett: {voice over} "Even Vader lied to me."
Darth Vader: {in flashback panel} Obi-Wan Kenobi? Hmmm. Yes, Our quests are linked. Starkiller and Kenobi travelled together on a decrepit Corellian freighter.
Young Boba Fett: {in flashback} Why couldn't you just shoot him?
Boba Fett: {voice over} "Two decades I maintained the rage."
Jango Fett: {in another flashback} He also betrayed your mother. She died because of his failure.
Young Boba Fett: {in flashback} Nooo! That's not possible!
Boba Fett: {voice over in flashback panel} "Meanwhile, Obi-Wan Kenobi hunted down my mother."
Boba Fett: {voice over} "How could I possibly get my revenge now?"
Boba Fett: {in flashback to just a couple of minutes ago} I must find Obi-Wan Kenobi!
Boba Fett: {voice over} "Then reality hit me."
[SFX]: Thunk! {Boba hits the sailbarge}