It's a good extreme example of something that the work place really claims that is way out of the bounds of what they expect you to do during work. On top of that, it's considered to be less appropriate than gossiping at the water cooler.
If an employee is given an hour lunch break off campus, and they use it to have sex, the only reason I can understand someone being mad is if they're jealous. Substitute {having sex} with {driving aimlessly} to {eating lunch} and it should be the same thing to the employer - the employee is off campus and not subject to workplace expectations.
