Christina Ricci once discovered a great way to get off work. "When you're an actor, the only way they'll let you off... is if you're disfigured in some way and can't be photographed that day," she explained. "I found out, by accident, that I was allergic to penicillin and my face blows up like I've been badly beaten. So I figured if I ever needed to get out of work -- I did travel with the penicillin for quite some time -- that I could just take it, have the bloated-face reaction, and they'd be like, 'Wow, we can't shoot with her today -- she's completely disfigured!' And then I'd go back to the hotel and they'd give me a steroid shot and everything would be fine."
[Sadly, Christina never actually tried it.]