She starts to suck his cock

The kissing soon stops and Christy gets down on her knees. She takes Rob's big dick in her mouth and slowly begins to suck it. Rob's penis size was already apparent from the start, clearly a larger cock than yours which was now being sucked on by your mom. She put her mouth on it and so much of his cock was still seen. It turns both of you on seeing how much bigger the guy is.

"So I've got a bigger dick than that loser?" Rob says while letting out a laugh.

"Hey, listen here, my son is not a loser!" Christy responds.

Rob steps away from you mom and her mouth.

"If you want this dick, you better talk shit about that loser."

"W-what?"

"C'mon, Christy. I know you want this man meat."

She hesitates a little bit, much to your surprise, before finally complying with your bully request.

"Come on, you have to be louder than that."

"My son has a t-..."

"He has a?"

Finally, Christy gives in and yells out "My son has a TINY DICK, not a tree trunk like yours, Rob! I want to WORSHIP your BIG DICK, fuck that loser of my son !"

"Now that's more like it" Rob responds.

Rob starts to bring his dick closer to Christy's pussy.