The 'innocent' smile caused Grantaire to laugh. He didn't buy that act for a moment. Reaching across her to take her hand with his free one, he mumbled, "Oh, I bet you would be," and he drew in close as if he were going to kiss her.
At the last second, with a hand on one of hers and one on her waist, Grantaire spun Musetta in a dance move reminiscent of salsa. He made sure to keep hold of her and that it was not too abrupt. Alcohol and sudden spins did not often make good partners with balance and gravity... as he'd learned through trial and error. No errors tonight, and Grantaire was able to keep her on her feet, smirking.