What does the term "flying birds" mean

http://www.urbandictionary.com/define.php?term=ounce+of+cocain

36 ounces of cocaine
I stand all day on the block and flip bird’s and ki’s

or

key of dope
birds go for 10,500 from me.

So now everyone at work thinks I’m sellin’ blow.Why is this still Italizized?
Can’t a nigga just make a livin without people hatin’?
D:snky: <— seemed appropriate