For once Inigo seems to realise what a signal Tidus is giving him means, since he does wait for a second. His facial expression is curious though - he recognizes that expression on the other boy's face, and he knows what it means, but he still has no idea where Tidus is going with this. Would he really tease this guy? This weird big green guy? That just sounds like signing his own death warrant.

.. except it somehow works. The big guy starts blushing. Inigo's eyes grow wider, evidently impressed by Tidus's power.

Until Piccolo speaks up. Inigo slams his hand on the table, standing up and pointing dramatically.

"Hey! Tidus is plenty cute!"

He probably thinks he's just defending his bro's honour, while - as usually - not really thinking about what he's really saying here. Other than just echoing the word Piccolo used, without his brain processing said word.