Yes, show him

"Yeah? You think that's hot? Check this out."

You whip out your own phone and find a picture of Ariana, looking for something not too provocative, but something in the same style as Kali's pic. You don't have a huge selection, since Ariana can sometimes be a little shy about having her picture taken, especially in erotic situations, but you do have a few, and after several seconds, you find the perfect one.

Ariana is a dark haired beauty, and you swear there's some Latina in her blood because her skin always looks kinda tanned. She has smoldering eyes, although in the picture they're glowering at him for taking a picture of her in a pair of lacy bra and panties. But she just looked so hot, you couldn't rest capturing the moment forever. She's the shortest of your group, so she doesn't have legs like Kali does, but in the picture she's a half turning away, with one hand covering her chest, and the side stance gives a excellent view of a bubble butt to rival Kali's creamy round ass.

"Wow, dude, you didn't have to do that. I appreciate it. though I don't think I'll be able to look at her without seeing her in her underwear."

He laughs, but you're not actually sure if he's joking or not.

"I just wanted to return the favor."

You move to put your phone away, but Matt stops you.

"Wait, you liked Kali's ass right? You'll like this photo then."

The next photo he shows you has escalated to Kali being completely naked. Her back is still towards the camera though so it's impossible to see her tits. She's on a bed you recognize as Matt's, and straddling a pillow. Her hands are both in front of her so it's clear that Matt personally took this photo this time. Her butt is slightly upturned, waiting for him. You gulp. It's a bit dark but you can almost make out her pussy lips between her thighs.

"That's a hot photo"

"Yeah it was on our six month anniversary. This pose really emphasizes her ass, and makes it look really full and round, don't you think? It might be bigger than your wife's ass, but it's hard to tell."

He's looking between the photo on your phone and the new photo on his, and you feel the pressure again to show off your own wife's rear. After all, if it doesn't bother him, why should it bother you? You're just two guys checking out two girls, right?