The Inimitable Tiff

Update. I … checked the OED, which just updated the much entry this year and has a section on this use:

colloq. (orig. U.S., freq. ironic). With a preceding adjective, infinitive verb, or noun phrase, forming an elliptical comment or question.  

The use was popularized by the film Buffy, the Vampire Slayer and the television series derived from it.

1988 D. Waters Heathers (film script) 1
God Veronica, drool much? His name’s Jason Dean.

1988 D. Waters Heathers (film script) 86 
Heather Duke. It was J.D.’s idea! He made out the signature sheet and everything. Now will you sign it. 
Veronica, (queasy) No. 
Heather Duke. Jealous much?

1992 J. Whedon Buffy the Vampire Slayer (film script) 8
A stranger, walking the other way, bumps into Buffy, doesn’t stop.‥ 
Buffy. Excuse much! Not rude or anything.

1992 J. Whedon Buffy the Vampire Slayer (film script) 25
Pike and Benny have entered the diner, quite drunk.‥ 
Kimberly (to the other girls) Smell of booze much.

1998 M. Burgess & R. Green Isabella in Sopranos (television shooting script) 1st Ser. 1 42 
Anthony Jr. Probably I can’t go to that dance now either. 
Meadow. God, self-involved much?

2001 Cosmopolitan Dec. 178
You’ve seen them: the kinds of couples who finish each other’s sentences.‥ Jealous much? Damn right.

Via ascendingcoherence on Reader.