How stupid can people be? Very, apparently...
Seriously people, here in the US, the employer is providing you with a PC and a network connection on their dime, and they expect you to do work on their behalf while on the clock. Not sit there and flap to porn all day. They will usually tell you that they are watching.
There was an incident back in the 1990's at my old employer which caused a bit of a ruckus. What happened was a group of technicians was watching porn on one computer, creating a hostile work environment. One employee told a supervisor and nothing happened. The they told that supervisor's boss and nothing happened. Finally, that employee told the boss's boss's boss and something finally happened. An investigation ensued and twelve people were sacked, and several others were suspended. After that, the entire company got a mandatory course in how to avoid sexual harassment in the workplace.
Seriously, how stupid can people be? Apparently very stupid.