Next time....
 

....I'm feeling obnoxious I'm going to a bar with 11 other people, ordering a dozen wings then telling them to split the check evenly.

Everybody gets one wing. Leave the last wing as the tip. Would that be obnoxious enough ?

I would give you the extra wing.

And when one of your party refuses to pay their share are you going to scream "I want my two dollars!"?

<iframe width="420" height="315" src="https://www.youtube.com/embed/KNQRqAoT-2c" frameborder="0" allowfullscreen></iframe>

Reminds me of a time in my twenties. At 1:30am, Jim asks if I'm hungry. "Yes". He replies, "Lets go to IHOP".

We jump in his 86 930 cab, scarf down, then the bill arrives. Neither one of us has a dime.

I had to leave my drivers license and return the next day to pay the bill.

Fuch Jim.

True story.

Where the heck did that extra wing you keep giving away come from????

New math!!! :D

or are they offering a baker's dozen?

Why would there be an extra wing? It's the OP and eleven other people. That's twelve.

Maybe I am missing something, like a back story or a regional expression.