singing flat

Singing slightly off-note. When this happens in published work (e.g. YouTube videos, CD's, etc.) most of the audience doesn't even notice, but people with a strong sense of pitch (most notably, perfect pitch) can easily notice this.

"Mark made such an awesome cover, don't you agree?"
"What do you mean? He was singing flat the entire song."

Flat as a board

Elise

Elise is flat as a board

foot flat

go as fast as you can go

foot flat on the gas!

flat yellow

The worlds greatest street ware clothing prodigy.

Fucking hell. You copped some Flat Yellow

Flat Canoe

When you take a hot iron and flatten your cock to make it longer.

Yo did you hear bernie gave himself a flat canoe and now his shit is 31 inches long.

Flat Egg

A member of the Thoha tribe, and a superior being of the bird-like Chozo race. Often mistaken by his nickname "Quiet Robe".

"I thought you were called Quiet Robe?"

"Nah fam, my name Flat Egg"

flat rat

A condition when hamsters are VERY happy and relaxed with their human friend.

First, they have to trust their human as a personal presence. Then, they have to trust that their human friend isn't going to suddenly become aggressive toward them.
then all you have to do is to pet them on your hand until they become flat.

bro you're hamster is a flat rat
they must be very happy and relaxed!