fish you could do carpentry with 是什么意思 第六季第二集里面

请大神解释一下fish you could do carpentry with
Sheldon: Oh,I was having a little troublesleeping,and I just thought,Uh, seeing as you're up, we could talk.
Penny: Talk about what?
Sheldon: Oh, I don't know.Uh, weather,uh, fish you could do carpentry with. Why Leonard is such an attractive anddesirable boyfriend.Yeah, pick one, your choice.