If you want to know why
plzsendtehcodez was created, just ask me.
I'm the one who created it.
Shortly before or after this question on Stack Overflow, I sat down and realized that we have a tag for homework, but we don't have a tag for when someone just wants you to do their work for them.
Humor and necessity created the tag.
At its peak, it was used by about 15 different high-rep users (I'm recalling from memory, as it quite surprised me when it 'took off' among the higher rep users), and it was on 48 or so questions.
Then a user who had it on one of his questions got upset that it was on there (though it was on there legitimately -- and I didn't put it on there IIRC), went through the system and took it off of every question in the system.
There were a few edit wars between this user and other users, as he was a lightening rod for activity (no, it wasn't RichB), and because I had a deadline at work, I decided to drop the issue.
Other users have since re-introduced the tag (in various forms, including the original), and there is another high-reputation front-page user that particularly dislikes the tag, so he removes it as soon as he sees it. Since he spends all day, every day on Stack Overflow, he has a lot of time to prune tags as he sees fit (no, it isn't Jon Skeet).
I even put in a Uservoice tag to settle the re-tagging issue once and for all (not just because of this issue, but of the gratuitous re-tagging done so users could get the 'taxinomist' badge).
In fact, I even had an email exchange that was answered by one of the newly elected moderators, even though I believe I had sent that email before the election.
Anyway, there's the history of why the badge was created, and what happened to it.