One of the challenges in the Saintsbook is to drive your car a certain distance on two wheels. I usually get a tiny 2-wheel distance every time I jump the car over something, but this seems like a really slow way to max out this challenge. Is there a quicker way to get my car up on 2-wheels and keep it there?
I found that the easiest way to complete this challenge was to do it through normal gameplay. Grab cars with loose suspensions (like pickup trucks, golf carts, SUVs, etc.) and powerslide (hold down Ⓐ on Xbox 360 or ✕ on PS3 by default; it's the handbrake) around corners a lot. I pretty much powerslide around every single corner in every single car. Doing this, I was able to get this challenge pretty quickly.
Occasionally, I was in a cars driving along the highway and had someone knock my car so it was tipping on its side with one set of tires on the ground and the other resting along the median/guardrails, which also allowed me to rack up 2-wheel driving distance. If you really want to try to grind this at once instead of doing it organically through gameplay, this would probably be the easiest way to do it. With a car with a high enough suspension, you can just drive halfway up onto the median/guardrail yourself and do it.