would be funny to make them signup for different payment systems...
"I only use paxum, signup for a paxum account and I'll send you $$ right away!"...
then 2 days later when he signs up:
"I'm sorry, but turns out I don't have paxum funds anymore, but I have some $$ in dwolla, give me your dwolla address and I'll send the $$ right away!"
then 2 days later:
"I'm having trouble sending $$ via dwolla, some "transaction can not be completed" error, do you use bitcoins? I can send you the funds using bitcoins right away!"
and so on...
could also make them sign a contract... then W9 form... then a copy of his drivers license... etc...
could have hours of fun with this...