After a bit of debate, Tooru.

Izuku got up off of Tsuyu, but kept a grip on her wrist. Not having heard the side bet, he mentally thought about Tsuyu's Quirk, and how he could have fun with it. "...Momo, I wish that Tsuyu's tongue was extra strong and durable, and erogenously sensitive at her will," he said.

Once Momo had snapped her fingers and granted the wish, Izuku turned back to Tsuyu, and ordered her, "Say "ah."" The moment she complied, he pulled her tongue from her mouth. Setsuna and Tooru blinked, neither having expected this. "Oh, and I wish I knew how to tie someone up in various Shibari styles," Izuku added.

"Done!" Momo giggled as she granted the wish again, already seeing where this was going. Izuku immediately got to work, using Tsuyu's own tongue to wrap up her body, making sure to loop it over and under her breasts, and pulling her arms behind her back, and wrapping them up in the tongue. Due to the wish he made earlier, this caused Tsuyu no discomfort. In fact, it made her moan as she was tied.

"...okay, that's... creative," Ochaco giggled. "Gives the term "tongue tied" a whole new meaning..."

"...so, who wins?" Setsuna questioned.

"Me, obviously! I said he would try out her tongue first!" Tooru stuck out her tongue at Setsuna.

"You obviously meant in a blowjob though!" Setsuna protested with a pout.

"True, but I didn't specify that, now did I?" Tooru smirked.

They stared each other down for several moments, before Setsuna sighed and said, "Fine."

Izuku made sure Tsuyu was securely tied up, and grinned. "Still feeling a little rebellious?" he teased.

"Unh..." Tsuyu moaned, clearly too aroused to do much now.

(Credit to Quiet One for the idea of tying Tsuyu up with her own tongue, lol.)