Flatty Light 

Beer, preferably natty light, that has sat in an uncovered pitcher or water jug for over 12 hours.

"I feel like this natty light lacks the delicious carbonation that I've grown accustomed to from this great beer."
"That's because it's flatty light!"

Flatty Light by Rundeezy September 30, 2011

fratty light

also called natty light. The frattiest of beer.

Pass me a fratty light.

fratty light by john_montana June 1, 2006