IN GREAT SHAPE

Marty, who's always been the runt of the litter, goes to the gym in a desperate effort to built some muscles (and some self-confidence); he happens to meet Sean and Kelly, a stunning couple, and a perfect embodiment of strength and height. Little do they know that, for some unexpected trick of the destiny, the gap in their size will actually increase as they get aroused, the puny man shrinking even more, and the giant couple's growing with their lust...