Rather than burn up energy being pissed, channel that energy into making them regret ever sending anything to you. I like BD's mailing campaign -- if they don't send out post-paid envelopes, I'm not sure what to do... I bet more creative minds than mine can come up with a few ideas. This could get interesting.... 
C'mon...who goes to the trouble of sending you crap and doesn't include a pre-paid return envelope?
What ever you do...do not send feces from any critter, human or otherwise. It's a'gin the law!
