Prank war, i need lottsa really good pranks to win this onee?

so me and my best friend just declaired a prank war and i need some ideas, i dont ant anything too mean, just funny outragous stuff! but i gont want to have to spend big $$ on props. she doesnt have a car, so no car ones, and i cant do anything too horrible because her mom would kill me and nothing that will hurt anyone. i dont want to cause hell, just irratate her and make her back out:)