My mom was a '(class)room mother' to help with school parties & such. For one Halloween party, she showed up for her room mother duties in a clown costume & proceeded to act like an idiot - well, like a clown would. My classmates were all laughing hysterically, completely entertained, but I remember being mortified! In retrospect, she made an awesome clown/entertainer. (That's just one of many embarassing incidents but the first that came to mind.)
What was your favorite Halloween costume ever?