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

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