He hears music, and it immediately draws him in. After a day of everyone giving him strange looks whenever he starts singing, it's a relief to hear someone else doing it, even if it is only in a karaoke bar, which he's aware is a more 'normal' place to be singing.
He wanders in, pleasantly surprised to see that it's Gaeta doing the performing, gets himself a beer so as not to seem too intimidatingly attentive, and then applauds at the end of it, smiling.
"Bravo!"
((OOC: Coming in a bit later, assuming Gaeta has actually found something to sing in the end!))