Stretchibitionist 

People who go to the gym to show off their bodies and get attention.

The makeup the stretchibitionist insists on wearing doesn't run and she never seems to break a sweat.

Stretchibitionist by Robert Lanham, Author of Food Court Druids, Cherohonkees, and Other Creatures Unique to the Republic August 4, 2004

stretchabitionist 

A person at the gym that stretches out in an obvious place, usually in front of a mirror and in a seductive manner, making sure everyone gets a chance to see them. A stretching exhibitionist.

Hey Betty, check out the stretchabitionist doing pelvic thrusts over there on the mats.

stretchabitionist by photojennalist March 10, 2009