That must have led to observers saying 'that's gotta hurt':
One of Lady GaGa knocked out one of her dancers' teeth during a US radio performance yesterday (March, 31).
The singer got a little over-excited during the set for New York radio station Party 105 and unintentionally hit the backing dancer with her mic, resulting in her losing three teeth.
Still, at least it was in a good cause, dancing for a radio performance. Presumably GaGa - like the audience - hadn't seen the dancer was there.