It's a dynamic phrase that could be used to say someone's attractive, or if food looks good. It's antonym is "cook it down" which could mean that someone's nasty, shouldn't sport that type of clothing, or if the food isn't as good as you thought.
(hot chick jogs by) "Mmm, cook it up!"

"What's for lunch today?"
"Chicken fajitas."
"Mmm, cook it up!"

(someone girl's pasty ass crack hanging out) "Uhh, cook it down! Cook it way down!!"
by ohdogmycats October 10, 2009
Get the cook it up mug.
preparing for a shot of heroin
Sick Boy: Say something Mark.
{shouting}
Sick Boy: Fucking say something, huh?
Mark "Rent-boy" Renton: I'm cooking up.
- Trainspotting (film)
by Harventh February 7, 2008
Get the cooking up mug.
A jailhouse term used by inmates to define a shared-feast, in which each inmate involved contributes at least one food item (like chips, ramen noodles, etc), which is then mixed together and enjoyed by all the participating inmates.
What's up, you got that noodle for the cook up tonight?
by lonster85 December 19, 2010
Get the cook up mug.
The state of being extremely high on meth or crack type drugs.
by Rev. Foxx May 20, 2010
Get the Cooked Up mug.
preparing a syringe with heroin or other injectible drug
Her baby died so I cooked her up a hit but only after I got mine; that went without saying.
by _GoD_ September 21, 2004
Get the cook up mug.