The blog has a few entries on badges that might help explain the rationale

http://blog.stackoverflow.com/2008/07/stack-overflow-badge-feedbac/

http://blog.stackoverflow.com/2009/12/badges-positive-only/

Badges exist to reward and encourage the kind of positive behavior we want in our community. But not everyone seems to understand that. It’s tempting to suggest “funny” badges which reward behaviors that, if you really sat down and thought it through, are actually negative.

A tiny bit of humor is tolerated there, ala Tumbleweed, but in general it's to encourage positive community behaviors first and foremost.

The blog has a few entries on badges that might help explain the rationale

https://blog.stackoverflow.com/2008/07/stack-overflow-badge-feedbac/

https://blog.stackoverflow.com/2009/12/badges-positive-only/

Badges exist to reward and encourage the kind of positive behavior we want in our community. But not everyone seems to understand that. It’s tempting to suggest “funny” badges which reward behaviors that, if you really sat down and thought it through, are actually negative.

A tiny bit of humor is tolerated there, ala Tumbleweed, but in general it's to encourage positive community behaviors first and foremost.