Where the exhausted sphincter muscle fails to close and quivers just like old toothless grandma's mouth puckering up to give her (revolted by the gesture) grandchild a kiss.
Kid B: really, what acts was she engaging in that would provoke you to recount this tale to thou my friend?
Kid A: this dude whipped his dick out of her ass & boy did it gape man! reminded me of my Granma's kiss!
Kid B: Stroll on.