inappropriate.

At school the other day I took my kids to play in the Fun Dazzle* room- essentially a climbing frame with tunnels, trampoline, slide, ropes and pool filled with plastic balls. As the nursery aged children are likely to run away we lock the door whenever we are inside, and when we arrived another nursery class was already using the room.
I knocked on the door, and a couple of my kids started knocking as well... as hard as they could on the aluminium sliding door in their excitement to get inside.
As Kelly, another nursery teacher, opened the door I said in a bright voice befitting a nursery teacher:

"We've got some good knockers out here!"

I swear I meant it in the nicest possible way.

*The Fun Dazzle room looks something like this, but without the annoying teletubby rides.