Having sex in a moving vehicle needs two important items: condoms AND a seatbelt.

Over last weekend, authorities in Bozeman pulled over a 22-year-old woman because they saw her swerving. She was intoxicated...but that's not really the point of the story.

According to reports, she also had two buddies who were HAVING SEX IN THE BACKSEAT while she drove. (They were literally having sex in the backseat, that's not a euphemism for sex in the no-go hole.)

And because they were having sex and NOT wearing their seatbelts, Alexis Kristine Cooper didn't just get a DUI . . . she ALSO got a ticket for a seatbelt violation. (If you're wondering, yes, in Montana cops can ticket you for having passengers in the backseat without seatbelts.)