I once had a patient who wanted to change his species.
I'll tell you, he was unBEARable.
Listen up, buttercup. This "joke" is a play on words. The joke teller had a patient that was "unbearable", meaning difficult to deal with, but it also sounds like "bear" because the patient wanted to change into an animal, get it? You probably don't. You're probably one of those guys that eats crayons.