At first Inigo truly believes this is just an educational process. Just Tidus showing him some candies that apparently the other guy knows all about, even though Inigo is seeing them for the first time.

But then, as his own brain is very, very slowly processing something, he finally seems to realise something.

"Tidus, you're eating all of them by yourself!"

Cue Inigo bodily throwing himself at Tidus to try and grab that bag back. Be careful, bro, or they'll both end up on the floor with the sheer force of Inigo's body throw.