Shag Happy

Shag Happy is a term used to describe a person who has casual sex but ensures that all parties involved are pleased with the later outcome and that there is clarity in where they stand. There are no crossed wires, nobody is getting screwed over and there is no ill feeling or 'bad blood' afterwards. There's honesty between the parties involved and no tricks, plays, mind games or deceit.
Being Shag Happy relates more to the approach of casual sex and is not exclusive to only ever being casual. Relationships can still form, whether romantic or platonic and so on.

The term is heavily inspired by the Austin Powers movies, in which the lead character regularly uses the British slang term 'shag'.

I had sex with Adam last night, but it's okay, he's shag happy so everything is cool between us.