Stands for gouch anus and sack. The procedure is performed by gay males. you start by making an 'ok' sign, then you insert your thumb and forefinger up your partners asshole. The middle finger is used to gently rub your partners gouch area. Last but not least, your ring finger and pinkey are used to gentaly lift and massage your partners scrotal area. The proper way to recieve G.A.S. is to hold the penis up with one hand while you use the other hand to stabalise your penis hand.
Patrick said to Jack "G.A.S. me baby!"