I'm FABULOUS

Someone: Happy birthday
Me: Same to you

"Thanks" usually works.

I just say something random then move away or continue babbling to make things more awkward

Waiter: enjoy your meal
Me: you as well

Me: Hello REDACTED
Him: Merry Christmas
Someone Else's Mother: Happy New Year
-
Me:
Me:
Me:
Me:
Me: wat

I just giggle and pretend I'm really shy because it's easier than having to come up with a verbal response

It is my birthday