Sherri Davidoff suggests that it’s routine for some companies to monitor their employees verbal mood (my emphasis):
Forensic investigators who are monitoring active connections can collect all network traffic to and from a specific computer, without the user ever knowing. There are many ways to monitor network traffic. If investigators have the support of network administrators, then the administrators can simply set up a SPAN port on a router, mirror all traffic, and filter for interesting bits. Some companies do this all the time, filtering for malicious traffic, proprietary data, or even keywords that might indicate employees are angry. Wireless networks are even easier to analyze.
“That’s Homer Simpson, sir. He’s one of your boobs from Sector 7-G.”