Remember kids: it is generally considered bad etiquette to skip out of a round when it's your shout.
http://www.newzimbabwe.com/pages/incest30.13114.html
"FAILING to buy your pals a beer can kill.
A Zimbabwean man from the small town of Chinhoyi tragically learnt of this rather late as his two friends hacked him to death because he had allegedly failed to buy a round of beer."