I am reading a book "Surely You're Joking, Mr. Feynman!: Adventures of a Curious Character" where an author wrote
So I could never understand why Tamara always went to the trouble of introducing me to all these nice girls, and then, even though things would start out all right, I would always end up buying drinks, spending the evening talking, but that was it. My friend, who didn't have the advantage of Tamara's introductions, wasn't getting anywhere either--we were both clunks
After a few weeks of different shows and different girls, a new show came, and as usual Tamara introduced me to a girl from the group, and we went through the usual thing--I'm buying her drinks, we're talking, and she's being very nice. She went and did her show, and afterwards she came back to me at my table, and I felt pretty good. People would look around and think, "What's he got that makes this girl come to him?"
So what does it mean to be a clunk (if I can use it so)?