Place traps like pissing in someone's drink, piss-filled water balloons, shaking someone's soda so it bursts when opened, tripwire-operated firecrackers, sticking something inside car exhaust(potato will make the car fire spuds after jammed for a while and jenkem will wreck the car), setting punji stakes(filled with glass, wooden planks, or shit), throwing lab mice or small dogs(like snark in Half-Life), placing spikes near a car, inserting gunpowder into car fuel tank, and some other shit.