This video contains language which is not safe for work. It is the opening scene from Reservoir Dogs.
Why Does America Have Tipping - Cowen - Note what he recommends you do at a place you will eat at only once.
What Happens When You Abolish Tipping
The Reverse Tip
Theory on Tipping?
$20 bill trick - Risky Tipping
Bonus content: If you really have time to burn, here is a Freakonomics podcast and more links.