The bullfrog is a sexual move where you place your scrotum over the womens asshole. She releases gas (farts) and the ball sack inflates making the appearance of a bullfrog.
An elaboratepuppetry of the penis trick in which one clamps the foreskin shut with their fingers. The performer then begins to urinate, giving the foreskin the appearance of a puffed up bullfrog.
The act of stretching one's scrotum/nutsack over a bitch's mouth; the effect is reminiscent of the inflation of a bullfrog's throat-bubble-thingy. Nooch.