Beeeeeeeeep...

From BluWiki

Beeeeeeeeep... is meant to symbolize the sonic output of an electroencephalogram monitoring the brain activity of Reds manager Jerry Narron.

Example in use: RR#1: Why isn't Milton being relieved? What's Narron doing? RR#2: Beeeeeeeeeeeeep...

Here is the origin of the joke.

Red Reporter keeps on showing brain activity, meanwhile...