A large bag of alcohol (typically wine), generally very cheap, rancid on the palate and housed (temporarily) in a box. Typically a lower socio-economic choice of beverage.
Often followed by violence upon or by the person consuming said flagon.
NB: Flagon can be inflated post-consumption to provide a pillow. Nice.
"Hey Morton you dardy mutt, come aroun' to our place and bring a flagon of woobla. Der's a party happening tonight"
Used when you cannot understand the pronunciation when an oriental person speaks.
From the Youtube hit and meme, Tuts my Barreh
*At a Korean fast food*
Waiter: Me saff yu. wot yu rike?
Bob: Sorry what was that? I just want one beef fried rice to go.
Waiter: Bif frai rai? Hokey. Anatha?
Bob: What? That's all
Waiter: Chenku
Bob: And asbestos flaygon you too