"Last night my friend and I were having girls night and we went to a local pub. So while we are ordering drinks, my friend hands the bartender a 20 and he gives her the change. I'm not paying attention and go about my drinking when my friend pulls me aside and shows me her change... $26. Thrilled she gives him the $6 for a tip, and runs away.
At first, I told her that she should point it out to the bartender, but being a little drunk at that point I ignored it. Now I'm feeling guilty because I know that he wound up 10 bucks short on his register drawer and probably will wind up bitched out by his manager all so we could drink a lot more.
To that bartender: I'm sorry for my friend, but thanks for the drinks."