Though she is not pregnant, I think she is trying to make a point to her bf/hubby with regards to natural childbirth. She is trying to simulate the aftereffects on her pussy from giving birth the natural way.
I know if my SO got pregnant, I would prefer that she gave birth the natural way. But many of my SO's friends prefer the C-section because it is convenient and is painless.
Her friends would discourage their hubbys' preference for natural childbirth by emphasizing if they gave birth the natural way, their pussies would become loose from the birth. Are these hubbies willing to sacrifice the wifey's current tight pussy feel just to have wife give birth the natural way?