When she was in mate middle school / early high-school my wife was basically free use with her small group of nerdy autistic guy friends. One of the boys had parents who both worked late most nights so they would hang out in the basement at his place, smoke weed, play video games, and casually fuck. Apparently it got to the point where she would strip as soon as they got out of school & into the basement, at least if the parents weren't home and she wasn't on her period.

They stopped when she started dating a much older man who didn't like her being a slut like that.