Berserk Button/Dragon Ball


 * In Dragonball Z, a key part of Gohan's character was the power he gained whenever one of his friends or family members was the victim of cruelty. He goes insane with rage, and usually the Big Bad or an army of his Mooks are left reeling or dead. It was this that allowed him to be the first to reach Super Saiyan 2.
 * Same thing happened to his dad in the Namek saga. Frieza just had to kill his best friend Krillin at the end of a chain of revenge attacks (killing Dende and severely injuring Piccolo) and then go on to threaten Gohan. Bad. Fucking. Idea. Just to prove he's Not Himself, he actually yells at Gohan to go back to the ship.
 * On that note, Goku had a similar berserk button pressed when Krillin was murdered by Tambourine, and (at least in Budokai Tenkaichi 2's GT story mode) when he learns from Android 18 that Android 17 murdered Krillin.
 * Vegeta gets one of these as well during the Cell saga, when Cell . Vegeta - who, up until this point, has either ignored or explicitly rejected any attempts by Trunks to reach out to him - absolutely loses it. Of course, his attack doesn't work, but it's a pretty critical character-defining moment.
 * Broly will attack anyone who so much as cries or looks like Goku.
 * Whatever you do, do not, I repeat, DO NOT wound General Blue's looks in any way, shape or form, or else you'll be extraordinarily lucky if Blue even decides to unfreeze you from his telekinetic ability and stop trying to kill you.
 * Don't hurt Mr. Satan when Fat Buu is around.
 * Do not hurt, kidnap, threaten, taunt or (Kami forbid) kill Gohan. Ever. If you do? Piccolo. Will. END. You. With EXTREME PREJUDICE.