this is old, certainly older than 2005. I have lost cont of how many times i have seen this it was mildly amusing the first time. the 200th, not so much.
June 15th always works for me. There's no better way of paying back some ignorant cock end who whacks their trolley into your legs than getting a load of random stuff and sticking it in their trolley when they're not looking. Well actually, cutting their brake cables is good for a laugh but it's quite difficult to locate their car and get into it without them knowing.
