Yes; it's time for Cara to return the favor

"That was amazing, thank you," you smile at Gabrielle as she tucks you back into your pants and climbs out from under the table. "You should see about adding that to the menu; you'd make serious bank!"

It was mostly a joke, but she really seems to consider it for a second. "As fun as that sounds, it'd be a health-and-safety nightmare! This was a one-time deal, sweetie; you're lucky my jaw was bugging me so much. If that's all you need, I'll be right back with your check."

You're more than satisfied, so you let her go and look back at Clara, who's still rubbing your feet.

"You can stop the massage now," you say.

"Thanks again for letting me practice," she smiles, brushing a strand of hair behind her ear. "It was kinda cute the way your toes curled when you, uh--- y'know..."

Cara actually blushed a bit, which was surprisingly cute. Somehow, it was perfectly normal for a stranger for you to swallow your load in a restaurant, but not for your friend to talk about it. This ring was going to take some getting used to.

For now, though, you wanted to test the second part of this ring's powers. Since the first thing you asked for was seen as a favor you're doing for them, it should entitle you to a favor from them. You just helped Cara out by allowing her to rub your feet, so she owes you something of equivalent value. It's hard to quantify these things, though; what's roughly equivalent to a foot rub?