Jesse: Do you like my ball?
Mike: Yes, they are very big. I can’t even fit them in my mouth. You bought a new ball, right?
Jesse: No, they do not leave me.
Listen up, buttercup. This joke is playing on "ball" meaning a spherical object, but Jesse really means his testicles. Mike didn't catch on at first and was just talking about a regular ball, but Jesse's last line makes it clear he was talking about something else. You probably still don't get it because you can't even spell your name right.