
I remember this from another forum, it was very fun

Rules are:
Each player posts two messages in his post - first one flaming the above posters' brag, and the other - own brag

Example:
Poster A
I made ten euros today!
Poster B
You had to sell yourself to do it.
I got my picture on the front cover of a magazine!
Poster C
It was gay porn.
...and so on.