On Phonelosers.NET, When I saw the thing for advertising, I got an envlope, Wrote "Cheer up UPL!" on it, Put a scrap of paper with "10$" written on both sides, along w/a smiley face, took a BIG shit in it. (It was a large envlope) and mailed it to them! Not sure if they got it... never heard anything back
I've never heard of a rule saying NOT to smear shit all over a dollar and send it to somone.
The water content of the shit would make the envelope really soggy, plus it would stink. The postal service would be forced to check it to make sure it doesn't contain anything illegal to send (organic items), see it was a shit, and not send it.
Well, I could see that happening if I put a whole turd in the envelope, but I'm talking about just taking a dump then swiping the dollar bill between my butt cheeks. If there's just a thin coating of poo on the bill, it shouldn't stink too fiercely or penetrate the envelope and, with any luck, the person will receive it, reach into the envelope, pull out the money, and get the poo on their hand.
It's all here in this diagram: