finer than frog hair
1. Very thin. "Finer than frog's hair" can also be used. I'm not a fan of fettucine—I like my pasta to be finer than frog hair.
2. Very good or excellent. Wow, that dress is finer than frog hair—you look gorgeous!
finer than frog hair
n. fine; good. (Pseudo folksy. Note the interpretation of fine.) This chair is just fine...finer than frog hair in fact.