what's his/her face
what's his/her/their face
A phrase used to refer to someone whose name the speaker does not know or cannot remember. And then what's their face showed up at the party and ruined the whole thing! Dave has been dating what's her face for a few months now.
what's his faceand what's his name
Sl. someone whose name has been forgotten; someone whose name is being avoided. Was what's his name there? I never can remember his name. I can't remember what's his face's name either.