When you are doing it with your lady, you cum/wait until her mouth is full of drool and/or load so she's foaming at the mouth, like Old Yeller. Then, once she is foaming at the mouth, you take her and shoot her with your load and she wimpers, thus putting her out of her misery. Shooting noises are optional, but really add the effect.
Guy: (to girl) why is your face so red?
Girl: I got Old Yeller-ed.
Guy: Sucks to suck.