Thanks for the link slowmotion. Seems like 'petit coquin' or 'petit rigolo' would be perhaps the closest, or at least the safest for me to use and feel comfortable with. I think you have to have a good grasp of a language and know how to manipulate it to be able to swear in a non-offensive, humorous way. I personally wouldn't risk it. Equally, I'd never try to translate a joke into French. I can be funny with quick, simple one-liners but nothing more complex.