I pulled an old trick on LAPD to prevent someone from getting a DWI.
A car load of partying guys picked me up hitchhiking one night, the driver got stopped and as it progressed he looked like a DWI goner, none of his friends would do anything, so I got out and started being belligerent about “probable cause” etc. and causing a big distraction, which shifted all their attention to me, I got slammed around a little, but eventually I was cleared and we were sent on our way, the driver had been totally forgotten.
My brother’s friend told a story about driving home drunk one night and he came upon a line of cars at a DUI checkpoint. He put the car in park and scooted over to the passenger seat. When the line of cars began pulling forward a cop approached and asked why he wasn’t moving. He said he was drunk and the guy that had been driving him jumped out of the car and ran away when he saw the cops. I don’t remember what the specific resolution was, but he avoided a DUI.