Buy a Shovel, a Tarp, Three gallons of Bleach, some Duct Tape and a pair of Hedge Clippers, take it up the the cashier and while she's looking at you very nervously, ask if Wal-mart offers a cleaning service..."you know, like Serv-pro...like it never happened?"
Delete System32 on the computer(if they run Windows), if they have Windows 95 or 98 then destroy the computer's BIOS (with Flashkiller(a virus that destroys BIOSes)