Fun with Conan the Grammarian

Are you serious? You don't know the difference?

Whose. Who’s. Which do you use and when?

The most common error in this regard is to use who’s as a possessive. Why? Because that’s the rule we learned in school: in order to make a noun possessive, you take out the Elmer’s Glue and stick ‘s to the end of it, like so:

That’s Vladimir‘s baby-blue Pacer. (That baby-blue Pacer belongs to Vladimir.)

But you must erase this from your mind. Who’s only means who is or who has. It never means anything else. Ever. Okay? Who’s is a contraction in which the apostrophe replaces the i in is or the ha in has. Examples:

Who’s your daddy? (Who is your daddy?) Who’s got head lice? (Who has got head lice?)

Whose is the possessive form of who and sometimes which. Definition: “belonging to whom or which.” Examples:

Zerubabel, whose last name is O’Reilly, did the Safety Dance. (Zerubabel, to whom belongs the surname of O’Reilly, did the Safety Dance.)

Whose Village People eight-track is that? (To whom does that Village People eight-track tape belong?)

So in the words of Brad in Fast Times at Ridgemont High: Learn it. Know it. Live it.