I wouldn’t really do this, of course. Just harmless nefarious plotting.
What I actually did was send in a letter politely explaining the situation, saying that I don’t want a refund, or free food or anything like that; I just thought I’d let 'em know about Worms, Inc. before someone else has an encounter with them.
The raisins story really made me squrim. I’ll gladly take the worms over that.