The individual providing fellatio must duck down during the act.
"Nah dawg, I was gettin' ducked by that hoochie Tanisha from 'round the way...she gives that good top, yo"
The "replacement" girl got Ducked.
Girl 2: Oh he Ducked me, for real. He went back to his ex.
Girl 1: Oh girl that sucks. Lyin', Cheatin', huzzies always get the good ones.