"A collection of insults 14" joke

Takes his imagination out for a walk and ends up being dragged around the block by it.

Talks to plants on their own level.

Team player... No chance he'll develop a personality on his own.

Teflon brain -- nothing sticks. -- Lilly Tomlin

The best part of him ran down his mother's legs. -- Jackie Gleason

The butter slipped off his noodle.

The cheese slid off his cracker.

The definitive answer is: Her glass is half empty.

The fan is working but the freon's leaked out.

The going got weird, and he turned pro.

The heater's plugged in but the rheostat's shot.

The perfect personality to write software manuals.

The space between his ears powers vacuum pumps.

The spit valve's fallen off his trumpet again.

The twinkle in his eyes is actually the sun shining between his ears.