He is first seen when he helps unscrew something stuck on the end of his mother Faucet. He later watches Faucet fill Robbie's bottle before the gang leaves to go to Mars. Near the end of the film, he is dripping and Faucet thinks he's crying, but he tells her that he actually needs a new washer. She then tells him that maybe Santa will bring him one.
Redmond O'Neal, Squirt's voice actor, is the real-life son of Faucet's voice actress Farrah Fawcett.