I have had someone on IRC contact me about sending me a check for BTC. He said it came from ACM (
http://www.acm.org), so I Google'd it and found this at the bottom of the page.
Check Scam Alert
The Association has become aware of a check fraud scheme where fraudulent checks that appear to come from the Association for Computing Machinery are being used to purchase items from Craigslist or possibly eBay. The Association does not make such purchases. You should contact your local police authorities if you receive one of these fraudulent checks.
Obviously, the user on IRC was attempting to scam me with a fraudulent check.
Just remember:
Never accept checks from someone that you don't trust.