1. (Verb) When a women acts upon (sucking, jerking, fucking) a man's penis and he does nothing but sit there and enjoy it.
2. (Noun) A man that never touches his genitals.
1. Guy 1: How was your night last night?
Guy 2: It was awesome, she librettied me all night long and I didn't have to do a thing!
Guy 1: Nice.
2. "That guy is such a libretti, he'll never touch himself leading up to the day he dies."