Place two flat benches parallel to each other and slightly less than one leg's length away.  Place both hands on one bench and both feet on the other, lower both arms until you feel a strong stretch (in the video, Ted is going down to a 90 degree elbow angle) and press yourself upward.

To add weight, lean back on one bench and put plates on the middle of your thighs or simply have your training partner place the plates on your legs.  The motion remains the same for the exercise.

In this video, Ted Toalston performs his last set with seven 45-pound plates stacked on his legs.  He started with no plates and worked his way up, adding one plate on each set.  This allowed his body -particularly his shoulders, elbows and chest- to get properly warmed up.

Used properly, this can be a great movement for your triceps and chest.  It's a variation from regular dips, but is still a great exercise.