Believe it or not, about 2 years ago, I managed to spawn some weird item (it sort of resembled a statue, although I've never ever seen it again...) in my inventory using artmoney. It was called "null". Of course, it was clearly 100% client side, and was incapable of doing anything. It disappeared on its own after a few minutes, and I've never been able to do it again.
I might have a screenie somewhere on my external harddrive. I can look if youre interested.