Green’s Dictionary of Slang

(Irish) the penis.

1988		R. Doyle Commitments 38: Tha’ alrigh’ for the blackies, Jimmy. – They’ve got bigger gooters than us.
1991		R. Doyle Van (1998) 593: Jimmy Sr got his hand under his gooter and yanked it into an upright position.
2001		G. Coughlan Everyday Eng. and Sl. 🌐 Gooter (n): penis.
2002		A.R. Becker Andrew M. Greeley 91: She plays with his gooter for awhile, lets him knob her,.