SOS! It seems like Rihanna won't be showing off any new dance moves this summer, as the dashing diva is hobbling around with an injured foot. Apparently she had a mean run-in with a chair while on vacation, and now she's clutching crutches instead of her umbrella. Rihanna's supposed to stay off her feet for at least two weeks, but that won't keep this Good Girl Gone Bad from taking center stage. According to TMZ.com, she'll continue to perform … while sitting in a chair. Ballsy! Better keep a close eye on that thing, lady, or it could get ugly!