I've done a lot of supply in schools and FE colleges.
One class I taught on a regular basis but didn't know by name. I went into the class room looked around and before I started the register said, "There don't seem to be many people here today, who's missing?"
Several students pointed to an empty chair and said, "the dark one", I was the only white person in the room and I very unprofessionally corpsed.
I've told this a number of times
Me:Did yoiu just say pheasant
Student: No Miss. What's a phesant?
Me:It's a bird, you can eat it
Student: Uhg, who'd eat a bird
Me:Do you eat chicken?
Student goes red and friends laugh
I did a one day cover teaching maths all day (subject not really relevant but it meant I stayed in one classroom) A year 9 class come in and as I'm taking the register I hear, "Miss, do you take it up the arse?"
I pretended not to hear but made sure to report it.
One of my main subjects is Computer Science, most trooms are aranged so you can't see the students screens but usually you have software where you can take over or freeze a screen and you can also project that screen onto the main white board.
I have been know to take over a screen and look for 'my little pony' before projecting it onto the screen when someone has been playing a game.
Obviously you need to know the class fairly well to do that.
My favorite classroom had all the screens pointing to the front so students had their backs to you when typing, they had swivel chairs so you could get them to turn round and not have any distractions.
Yep 17 years old and it hadan't occured to her that chicken is a bird.