I laugh at myself then tell her I'm nervous because she's so cute, apologize, and ask to try that again. Most girls like several things about that. One, I'm ok with making a mistake. Two, I'm ok with laughing at my mistakes. Three, I'm attracted to her to the point of fumbling my tongue. If I did it on purpose I'd be a frickin genius, but alas, I'm a goober that speaks my heart.