What's his/her/their face phrase informal slang spoken
Used to refer to someone whose name the speaker forgets or do not know.
Are you still dating what’s her face?
Did you and what's his face steal my brand-new laptop?
Are you still working for what's their face?
To mess a speech up or forget the words that one is supposed to say
A mock title that is used to refer to a self-important person, especially who is demanding and tyrannical
If you say something slips your memory/mind, you mean that it is forgotten.
To use a specific name for someone