It is common civility to say thank you after being addressed as a putangina.
Filipino 1: Putangina yang banyaga na yan! (Wow, that foreigner is handsome!)
Filipino 2: Tama ka nga! (You're right!)
Foreigner: Excuse me what are you saying? I can't understand...
Filipino 2: It means you're handsome.
Foreigner: Thank you!
Filipino 1: Putangina talaga yang *insert foreign celebrity name here, i.e. Justin Bieber*! (That Justin Bieber/other celebrity really is handsome!)