Brain Transplant

I wasn't going to have a brain transplant...

But then I changed my mind.

Brain transplant
Brain
Doctor
Hospital
Surgery
Mind

Explanation

Explain Bear

Hey, dummy! This is Explain Bear here. The joke is that the dude wasn't gonna get a brain transplant but then he changed his "mind". Get it? "Changed his mind" but he's talking about a brain. You probably think mayonnaise is an instrument, huh?