It's rude to sleep with friends of a friend.
Carolyn who is Dave's friend asks Dave's other friend Jim to hang out and maybe have sex tonight.
Jim wants to respond to Carolyn's proposal.
Jim tells Carolyn that out of respect for Dave they shouldn't really get involved with each other that way.
Jim tells Carolyn that he thinks that's a great idea since he finds her very attractive.
Dave is delighted that Jim is doing what he can to maintain the trio as a good friendship.
Dave is sad that he seems to be left out of the trio now as two of his friends are hooking up.