You shouldn't be vengeful.
Victor's boss, who is normally a nice guy, did something that Victor didn't like, making Victor angry.
Victor wants to be free of his angry feelings.
Victor thinks of the good things that his boss does and figures that the event was a one-time thing.
Victor takes revenge by urinating into his boss's coffee in the morning and feels better.
Victor calms down and maintains a close relationship with his boss.
The boss drinks unsanitary urine and wonders why his coffee is so disgusting that morning.