Often referred to as a Russian dip, this exercise is great for anyone with aspirations of progressing to a muscle-up. It takes you through that awkward transition of being parallel with the bar to being over top of it.
First timers will want to do a serious shoulder warm-up before attempting this exercise, along with several reps of traditional dips with a maxed out range of motion at the bottom. Though they look relatively easy, that roll from forearms parallel to perpendicular (and visa versa) isn't easy.
Start at the top position on your first set and try a slight lean back on the first few reps. Progress 10-20 degrees further each rep.
This can also be performed between two benches stacked on boxes, which is much more comfortable when you're starting out, and gives you the ability to progress all the way down to the inside of your upper arm, like gymnasts do on the parallel bars.
If you have a choice, start out with a wider grip (wider bars).