Hospital Bills

Noah (age 9):

Me and Ransom used to play this game at recess called hospital bills. We pretend that the ground is hot lava and then we go on the zip line across it.  Right before you go you name the price and say, "Hospital bills, go!" and if you land in the lava you have to pay it.  Not really.  Just for pretend.  But if you make all the way across the zipline then you say, "Back in the bank."

What?  What's so funny?  We've been playing this for two years!