Typing it out and using a tool to translate it reveals the message:

BE SURE TO DRINK YOUR KUMATINE

Mysterious.

This is in fact a reference to A Christmas Story, in which the protagonist Ralphie gets his decoder ring and feverishly tries to decode the radio's message. The message turns out to be "Be sure to drink your Ovaltine" - a very disappointing advertisement, rather than the 'spy' message he was hoping to obtain.

"Ovaltine? A crummy commercial? Son of a bitch! "

Kuma is Japanese for Bear (Mono kuma - Mono Bear), which is where that part of the message comes from.