I remember a story very similar to this that happened to me on Diablo2. I was in a public game and this guy came to me and said "I know a trick to dupe your items"
Me: sure.
Him: yeah it's true all you have to do is fill up your inventory and let me kill you
(Note: for the non-D2 players of you, what then happens is that all the equipment you're wearing ends up on the floor instead of your inventory, since it's full... and the other guy can thus steal it)
Me: Oh really?
Him: yes really. Come on!
Me: I know the trick, dude. Sorry.
Him: oh yeah? Aha ha sorry I tried to set you up, sometimes it works
Me: yeah, sometimes. But it is a well-known one.
Him: well let me show you another one, then. Look, if I go here behind the fence (goes there) and drop my equipment on the ground (drops the equipment on the ground) then I can not take it back because I'm on the other side of the fence!
Me: Really? (grabs equipment) Oh yeah, true.
Him: WHHAAT?