My personal favorite comment like this is when I have kids making the switch from all star to school cheer and aren't used to the dead mat.
I TELL kids at the pre-tryout meeting that dead mat/hard floor tumbling is different, and to try and get in some dead mat time BEFORE tryouts/clinics (because nothing is worse than showing up to a clinic having NEVER tumbled outside of springs.)
However, without fail, there is at least one person who just cannot process what she's being asked to do.
It goes like this:
"So you mean, I have to throw my tuck on this mat?"
"Yes."
"How am I supposed to do that?"