This was new.
When I was teaching grade 8 I went through a month of pranks with them (as in them pranking me on Friday's by pushing tables up to the door of the room so that I couldn't get in... except I could because there was a 2nd door, they also strung tape across from my desk to a counter at ankle level so that when I walked by... and I did... I would get tape on my pants. They thought it was hilarious). But I digress.
My grade 11 Social Studies class almost got me.
It was a quiet class with about half of them missing (likely due to the fact that they were writing a test). Anyways, at the end of the period one group of boys decided it would be funny to take the cap off their water bottle (their water bottle still containing water) and turn it upside down (so that when I grabbed it the water would spill everywhere).
Unfortunately for them they never even got to witness me discovering their little prank because I never did. What they weren't counting on was another very helpful student that noticed the prank and cleaned it all up for me.
Better luck next time!