As a college student, going out to dinner with a group of friends is great. Until the bill comes.
Now, as a student, everyone (including me) is short on cash. But you'll still see two different types of people when it comes time to pay.
Mr./Miss Save-a-Buck: The meal was $12.99. These people pay $13 – $14 if they're feeling generous – thinking that they paid their fair share.
Mr./Miss Considerate: The meal was $12.99. They contribute $20, thinking that they paid their fair share.
At a restaurant, the price on the menu is not the price that you have to pay. It's the price on the menu, plus tax, plus a 20% tip, plus whatever drinks that you had, plus that appetizer that we all split.
Undoubtedly, your group will have a mix of Considerates and Save-a-Bucks. And unless everyone is a Considerate (which I have never seen happen), your group will have a hell of a time figuring out how to cover the bill at the end of the night. The pile of money in front of the poor soul who has to figure everything out (do everything that you can not to be this guy/gal) is inevitably way too short. The Considerates then throw in a couple extra dollars to cover the bill (they're considerate, remember?), further subsidizing the Save-a-Bucks' meals. And the tip rarely reaches even 15%.
Having worked in a restaurant, I can safely say that this is the worst. Unless the service really was awful, tip 20% . The waiter or waitress makes less than minimum wage and needs the money more than you do. Don't let your selfishness or miserly tendencies screw over someone else.
More embarrassing is when this happens outside of the US. When you're traveling with friends in a poorer country and have a pile of money on the table that equals what the server earns in a month, please don't start shouting that you need your change back from the group. It's the equivalent of 37 cents. Let it go. Yes, I've seen this happen. Yes, I scooted my chair back, pretended that I was somewhere else, and cringed. Behavior like this only adds to the "Ugly American" stereotype, and can ruin an otherwise great restaurant experience.
If you can afford to eat out, you can afford to pay for your share of the meal. Including tax and tip. Toss your good friend Mr. Jackson on the table and be done with it. It makes life a whole lot easier for everyone involved.