here's the deal with pranks, they should come at YOUR expense, not at the expense of others....... cant shit on people and expect them to laugh it off. HOWEVER, you can defecate on yourself and have people laugh it off....
"Just for laughs" was a prank tv show that specialized in that stuff, and it was ALWAYS funny because it wasnt at the audiences expense. Humor 101, when unfunny people try to be funny, this happens.