Q: What do you call a bunch of chess players bragging about their games in a hotel lobby?

Q: What do you call a bunch of chess players bragging about their games in a hotel lobby?
A: Chess nuts boasting in an open foyer!

This is a pun based off of the song "The Christmas Song," which starts out "Chestnuts roasting on an open fire." This is not a mondegreen because I doubt that anyone ever misheard the lyrics this way - Nat King Cole annunciates very clearly in the recording of this song which is played all over the place.

The humor in this joke lies in the fact that the jokester was able to provide such a long pun - 7 words is pretty surprising.