definately one arm pushups...or how about those pushups like the marines do where they like "jump"up and down on their arms? (<<best way i can describe it sorry)
I figured he just meant a push up with one foot off the ground. It's a variation used to make it harder (provided you don't put the elevated foot over the grounded foot), but it doesn't increase difficulty anywhere near as much as taking one hand off the ground does.