The best one though, happened several years ago when a friend and I were putting together a foaling kit for a 4-H project. Most of the things we needed we already had laying around the house, but we were missing a couple of items. So we went to Wal-Mart and walked up to the cashier with nothing but some KY jelly and an enema. As she was ringing us up she said "I don't even want to know what you two are up to" We just grinned as we paid her and walked off, giggling uncontrollably. We honestly hadn't thought how bad that looked before she said something.
Now, I know I'm not the only one to get some strange looks when buying horse related items. Share your stories of when your purchases might have given people the wrong idea.