The person offers to buy something from you and sends you a bad check for more than the item amount and wants you to send excess funds to shipping company via western union.
Educational post:
You may have been exposed to scam #1, as described here:
http://phonehelp.2truth.com/facts_rev.html
Remember to return here, to 800notes.com, after you look at any of the information at that site, either to post more information, or to let us know you avoided the scam, or to read any further information about that number that others may post.