i'll second the rotted fish or some poo in the car. something few people realize but that works well is hard boiled egg yolks. put them in something airtight and warm for a few days and you have a homemade stink bomb. however making a car stink and stealing plants are not equal to me, so you might want to follow up with some paintballs or BBs or bologna on the hood. if you really want to fuck the car up just pop the hood, smash and cut a bunch of shit and then dump tar or molasses everywhere in there, in every reservoir, every nook and cranny. then throw birdseed and dirt in there. then spit on it.