what's his/her face
A phrase used to refer to someone whose name the speaker cannot or does not remember. And then what's his face showed up at the party and ruined the whole thing!
what's his face
and what's his nameSl. 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.
ˈwhat’s his/her face
(spoken) used to refer to a person whose name you cannot remember: Are you still working for what’s her face?