How to get revenge?????? Please answer soon!!?

Ok, so here's the situation! I have a treehouse and me and my friend were having movie night up there, our annoying neighbors (same age as us) decided to through a large amount of balls, rocks, and sticks at us for about an hour. then my friend got a nose bleed and had to go home, so i went back up, got a magority of the things we left up there and went inside for the night. this afternoon after church i went back up to get the rest of it only to find about 10 of my paints scattered around, a wall of my treehouse painted an ugly brown-red. and a note im asuming said "i hate u" they spilled the snacks all around and ruined one of our good blankets, and i just hate that they have been going up there without asking. they have a treehouse too i want to get revenge......