RUMTICURiMMT2NFURSMTSIOIPTU

I remember seeing that on a sign that someone was holding at a high school play when I was younger. Here's the translation:

Are you empty? I see you are. I am empty too? And if you are as empty as I, oh I pity you.

I'm wondering what play (or musical) that's from. And shockingly I didn't find the answer by typing it into Google!