What is a quarter note?

An absolutely horrid family music group is recording. Their complete lack of music abilities is almost rivalled by their instrument’s lack of intonnation.

They were at another studio run by a dude I know but he apparently stopped working with them…

Me: Ok, you’re off the click. The click is counting quarter notes and your down strum should be right with the quarter notes.
Client: What’s a quarter note?
Me: You don’t know what a quarter note is?
Client: No
Me: Well, shame on your music teacher for not teaching you what a quarter note is!
Client: Uh, I’m self taught.