How can anyone in college not suspect that sending money to strangers in Nigeria might somehow involve something illegal?
Insert Einstein quote about infinite stupidity here.
Seriously, there are just some people that "smacking with a clue by 4" shouldn't just be a metaphor. If you accept a deposit into your account and forward it to Nigeria via Western Union, the punishment should be that the victim gets to use an actual 2x4 on you wherever he wants (in addition to any criminal penalties).
Alternative proposal: We open up Craigslist ads for "Earn money by getting deposits into your bank account and forwarding them to Nigeria." Anyone who responds to them is banned from using the Internet for a year and is added to a permanent blacklist that Western Union must check against before doing business with anyone.