Any advice on running a Therapy Session?

So my players met the world's very first psychologist, a hobgoblin who seeks to understand the inner workings of the mind and explores consciousness through taking every drug he can get his hands on, and obviously signed themselves up for a therapy session.

The first half of the session will be talk therapy, and the second half will be a series of trippy dream sequences tailored to each players backstory/favored playstyle. I've got the second half mostly figured out, but I'm a bit stumped on the first part.

The session is going to be mostly silly antics, but I think it'd be fun for the psychologist to poke at more serious questions just to immediately take the parties answers in a completely different direction.

Understandably I can't find very many tips on how to run that, can't imagine this is a common scenario, so I'd love some input.
What are some good questions to ask, or funny bits to put in there?