Instead of "that won't work" say "you can certainly try"

Don't put this out there, I can't let my players see this!

"Are you okay? This is the fifth time you went to the bathroom this session."

I hate it when the "and this is where we end the session for tonight" part happens 10 minutes in... once had a high level party teleport to the complete opposite side of the map 10 minutes after starting... That is when I learned what high level really meant.