When you are mistreated, given bad service, or get in a fight with a tip-able employee. You aggressively over-tip out of anger to show that you are better than the person serving you and to make them feel like a lower life-form...a complete loser.
"The cab driver got mad when I tried to pay with a credit card, angrily whining and saying "I need my money now and they take a cut when you do that." So I gave him a $20 Spite Tip and called him a poor loser, told him this is why is wife left him and he'll probably die alone"
The waitress was being a bitch all night so I gave her a 50% Spite Tip to make her know I'm better than her and that she is nothing compared to me