Pair programming ping pong combines the two practices of TDD and pair programming and turns them into a fun, collaborative game. 

What you'll need: Two software developers, one computer
Setup: The usual pair programming setup

It starts in the usual pairing way, with the two developers using one computer, one acting as the driver, the other as the navigator. 

We play ping pong in the following way:

• The first developer writes a new test. It fails because there is no code to fulfill it yet. The keyboard is passed to the second developer.
• The second developer implements the code needed to fulfill the test.
• The second developer then writes the next test and sees that it fails. The keyboard is passed back to the first developer.
• The first developer implements the code needed to fulfill the test and so on.

In the usual TDD manner, refactoring happens after the code to fulfill the test is written.