The cock comparison.

You get beneathe the covers of the bed as Heather explains how it'll play out. Most of your body is hidden completely as the scene starts.
"Oh, honey, wake up!" Heather cheerfully delivers her line as she walks into the camera's view. "I have someone I want you to meet."
"W-who is it?" You play along, too scared to challenge anyone.
"Remember how you wanted a threesome, darling? Well, I found just the right person..." Simon steps into the scene at his mark.
"An Asian guy?! But, honey, I thought it would be another girl! And he won't have a big enough dick to satisfy you!" Oh, God, why aren't you stopping this?
"Hey, I got the biggest cock in the state, and it's much bigger than yours, too!" Simon smugly gives his line.
"Why don't we measure them both?" Heather giggles. "See who's the champ and who's the chump?"
"Fine by me." Simon replies, dropping his pants as your wife grabs a tape measure.

Simon goes first, hard already as he removes his underpants. Heather grins widely as she reads off the tape, "12 inches long, honey! He really is giant!"
And now for the big reveal. You throw off the bed covers to expose your naked, girly body...and worthless mini-dick.
Simon laughs so loud it nearly splits your eardrums. "What a joke? You can't even pretend to fuck a woman with that teenie-weenie!"
"Teenie-weenie is right!!" Heather announces as she measures you, "You only got 2 inches here! He's six times longer than you!"

Simon sits down on the bed next to you, presenting his mega-sized organ.
"Try jerking me off, see how it feels in your hands. Before I fuck your wife, you get to appreciate how much more of a man I am!"
Heather squeals with delight, "Ooooo, yes, honey! Jerk that monster off! I'm gonna have so much fun feeling it stretch my pussy!!"

With both hands, you begin to fondle that awesome cock. Your slim, hairless and dainty hands caress Simon's amazing manhood, the Asian horse cocky you could never compete with. You're gonna pay proper tribute to it - this delicious and mighty flesh pole - with the best handjob you ever...

This isn't penis envy anymore. You have a real sexual interest in his dick now. You really do want to submit to this huge cock. You really do want to deep throat it, stroke it, take it in your ass and swallow his cum! That DIME-53 must screwed up your sexual orientation, too!
Your extra-puny shrimpdick leaks a tear drop of cum as you realise you have no hope of escaping the Mandingo Society and their stable of hung studs. Heather will not only keep cuckolding you, but you'll join her in servicing all their massive dicks.