Edit: "Fixed some typos."
TL;DR You can get mugged by your own mugger, and you can jack police vehicles from police during Lester's "cops turn a blind eye" mode, and ride around with other officers in the vehicle.
SO, me and dad (or dad and I) were screwing around. He called his mugger on me while he was sitting shotgun in my car as I was doing a doughnut. (donut?) The mugger came up to the left side of the car while I was still turning, and he ended up on the right side of the vehicle. He then jacked my dad out of the car, (assumingly trying to get to me) takes 500 bucks from him, and me and the mugger (or the mugger and I) burn off together. XD The mugger just sat there in my passenger seat while I drove around with him. Apparently, you can be mugged by your own mugger.
After this little revelation, we tried some other combos, some even involving Lester's no cop ability. Got a mugger to steal my car as my dad remained the passenger, and the mugger drove off with my car and him in the passenger seat. It didn't always work, as sometimes the mugger would cause my dad to step out of the car when he entered it. You can also have an officer in a squad with you, and not get in trouble in "turn a blind eye" mode. You can even jack a police car from an officer and not get in to trouble. So we made a little combo of trying to get me sitting in the back seat, an officer in the passenger seat, with a mugger as the driver. It only lasted a brief moment after multiple attempts because the officer turned hostile after the mugger mugged my dad (the driver) but it was pretty funny nonetheless. I don't have pictures as I was the one in the car just about every time, and as you know, you can't look backward with the phone camera while in a car.