This needs a bit of bg.
I am a Sec Sci teacher of 13 yrs exp. A colleague was discussing his teenage sons and their friends. He said that if he decided that he didn't like any of them (the friends) and they turned up to his house, he would just tell them to "piss off".
I commented that this may result in his sons (they were 13 & 15 at the time) wanting to spend time with their friends away from the house, and so my colleague would have less of an idea of what they were getting up to.
Apparently, this was too much of a reasonable suggestion, so he resorted to the old classic of "Well, you're not a parent so what would you know!!" Uh-huh, but I was a teenager once, so I abandoned my usual reserve and said
"No I'm not a parent, but I've never had genital herpes before, yet I can teach the causes and symptoms to my students" I turned on my heel (I stood up while I was speaking) and left the staffroom.
Apparently, the tumbleweed in there while this guy sat there blustering and being all affronted was ace. He's a very negative man, and not very well liked. Sure that has nothing to do with it. 