I didn't think of this exercise although I will take credit for giving it a better name than it previously had. Matt Furey referenced it in his book "Combat Abs" with an unweildly title. It isn't a very catchy name if you ask me and since it is very similar to the bridges in the muscles that it works, I thought it ought to be elevated to the bridge category.
Anyway, it's a remarkable exercise. It's pretty simple to do.
1. Find two chairs (or something like that) of equal heigth. Lawn chairs work particularly well since they're softer.
2. Place them a comfortable distance apart. The closer they are, the easier it will be for you to bridge between them.
3. Place your neck on one of the chairs and place your feet and/or ankles on the other, bridging the chairs. Your body should be completely straight between the chairs. Breath naturally when doing this exercise.
This is an advanced exercise but it is well worth trying. It hammers everything from the neck down to the hamstrings. Unlike the other bridges, it hits the obliques more directly.