4 stations.  Max reps at each station for 1 minute.  At then end of the minute, rotate to the next station without rest (you have to move to the next station fast to maximize rep count).

4 rounds through all stations, with 1 minute rest between rounds.

Stations:

GHD Hip Extensions
Hanging Leg Raises
Turkish Windmills
Ab-mat Sit-ups

Post total rep count from entire workout to comments.