It definitely takes a few moments before Inigo realises what Tidus is doing. He's so caught up in his panic that the sound of Tidus's laughter only enters his ears a few moments after it actually starts. It makes him stop shaking the other - though the hands still linger on Tidus's shoulders - and instead freeze up for a moment as the realisation slowly starts to hit him.

He's been fooled. Bamboozled. By the evil mastermind named Tidus..!

"Tidus!"

Now Inigo sounds exactly the same as a moment ago, but for an entirely different reason.

(Please, Tidus, don't lean this closely against him, oh Naga, sweet Naga, help--)

"How could you do that to me! I was really panicked!"