I sent a dirty joke to our female boss from a coworker's email.
I really hope you're kidding. Why would you do something like that?
I think it would be funny if the coworker got fired.
You shouldn't misuse emails to try and hurt a coworker. You should really get in trouble for doing that.
No way, I'll never get caught.
It's still wrong, even if you don't get caught. Your coworker and your boss are probably both very embarrassed by the situation. I think it would be good if you apologized to both of them.