Who's Gym?

"Brian, why don't you just join my gym," Jane asked, trying not to implore.
She could have asked when I wasn't naked. "I've been working out," I said as I reached down to pull up my pants.
"Oh."
"Oh what?"
"No. I see. Wait-- yes: I see!"
"What?" I remained doubled-over, fiddling with my sock.
"I think I see a six-pack," she nodded.
"Really?" I stood up, excited, and proudly turned to face her.
"Oops. It's gone," she shook her head, "Must have been rolls of skin."
Grrr. "There's muscle there!"
"Yes, dear. And it's a big one. Hee-heeee..."