She takes him to the basement gym

"Come on Billy." his big sister said, "I really need your help."

Tara took Billy buy the hand and led him out of his room and down to their basement gym.

He was wearing just his briefs as he looked over his sister's incredible body dressed in her sports bra and little G-string. Her massive DD breasts semed to barely be contained within the confines of her bra. Tara's body was fit and toned to perfection by her regular workouts and practice sessions. She was muscular yet feminine at the same time.

Billy watched her naked ass sway in front of him as she walked in her sexy 5" heels. He always thought it was strange that she'd chose to wear such shoes whenever she worked out with him but he never questioned it.

He followed her down the basement stairs and onto a large workout mat.

"Lets start with a few wrestling moves first." she suggested as she stood on the other side of the mat facing him with her hand on her hip. Her body glistened with sweat and Billy saw her erect nipples poking at the tight fabric of her bra. Tara's large wedding ring glistened on her left hand.

Tara smiled as she saw that her little brother's cock was begining to stir in his underwear.

"Hmmm." Tara said as she looked over Billy, "It looks like someone is happy to see me and wants to play."

Billy glanced down at his erection and tried to cover the bulge in his shorts saying, "Tara I...I'm sorry."

"It's OK bro." Tara siad, "It's nice to know that you like my body. You do like my body don't you?"

"Er...yes I do." Billy admited as he looked over the muscular sex goddess standing before him. Even though she was his sister he still thought she had an incredible body.

"Well...." Tara began, "I have a special treat today if you help me exercise."

Billy smiled as Tara ran her hands over her bra covered tits.

"You like these don't you?" she asked as she squeezed them.

Billy nodded yes.

His sexy sis turned her back towards him and then quickly pulled the sports bra up and over her head tossing it on the floor.

Billy's eyes grew wide as he looked at Tara standing in just her sexy heels and tiny G-string. He knew that today's session would be one he wouldn't forget.

What do they do next?