ok i've tried this many times before and all my family freaked out its really funny!!!hope u enjoy!!!
Step 1: Things u need
you will need a dollar bill and a toilet paper roll
Step 2: Setting it up
ok now get a toilet paper roll that is currently being used roll some paper off the roll but make sure it doesn't break now put the dollar bill in the roll and roll it back up and act like nothing happened after u r done.
Step 3: The funny part
just wait till someone goes #2 in the bathroom that u set the prank up in and you will hear a "OMG!!!" or "what the!!!" hope u liked it!!!
http://www.youtube.com/watch?v=c3y0CD2CoCs
Sorry to be so pernickety, I like the Instructable! ")
Also, forgive me for thinking that the pot may just be calling the kettle black a bit there "CodeKid1001"...