Foam Sealant Prank
More about Foam Sealant Prank
Pick up any can of foam sealant from your nearest hardware store. Then find a victim to prank and spray the sealant in either their shoes, wallet, pants pocket, purse, hat, etc..... Just get creative on how you want to prank them. The foam will expand and get rock hard.
To see an example of what the foam sealant does, check out this video of this dude pranking his gf by spraying it in her purse LOL http://www.youtube.com/watch?v=q0LxMpjo2Vk