When a guy fucks a girl doggystyle and grabs her titties one by one as they shake.
Mike fucks Anne from behind monkey barring her, as her tits jiggle he grabs the left then right alternativley.
verb; to set up another relationship before the present one is over
just as monkeys dont let go of one branch til they have another in sight, some girls/guys dont let go of a relationship until they've found the next
ie .. "that bitch melissa is totally monkey barring her boyfriend with that new guy, what a fucking whore"