Cost of Endorphins

I was talking to my friend on the phone. My mom comes and sits next to me and tells me to tell my friend a funny story.

Me: What? I don't want to repeat a story. You want to talk to him?

Mom: No! Just tell him.

(My mom feeds me the story line by line and I repeat the sentences. After the story is over)

Mom: Did he laugh?

Me: No. That story wasn't funny. He says that the protagonist is just stupid.

Mom: Well, I feel bad for your friend then. If he had laughed he would have released $2000 worth of endorphins. (and laughs)

(Now you know where I get it from.)