Since this is my natural way of sitting, I've essentially run through just about every possible way to slouch that wouldn't require defying gravity. It usually manifests in a manner pretty similar to Alucard's in
Symphony of the Night, although the foot not on my knee is usually either dangling in the air or braced against the nearest stable object as I'm rather short. I've even ended up doing a full blown
Slouch of Villainy ''upside down'' in particularly comfy (and very stable) chairs/couches, legs crossed and all. I don't recommend doing the last one as it can be rather difficult to get out of and you're going to be pretty dizzy from the blood rushing to your head.