How do you tell your girlfriend that you just had sex with your gym partner?

[GirlyGymRat]

I need a male training partner. LOL

[Hazard]

I need a male training partner. LOL

[Honkey_Kong]

I need a male training partner. LOL

Want to go to the "gym?"

[TheChosen1]

Been there-done that. But that was like 23 years ago for me. And it wasn't a very good experience for me.
I knew my gym partner since she was a sexy, hot 17 year old virgin. By the time I'd "hit it", she was a 21 year old cute but chunky gym partner who'd been far beyond virginity by then.

As for your question.......If she don't ask, don't tell.
However, if she does ask, take the Shaggy approach and in a stern voice say, "WASN'T ME!"