I find the changes in "favorite" phrases of the river guides interesting. Last time I was here, there was a lot of "FAF" talk, where FAF is an acronym from Farting Around Forever (or, of course, the more offensive F word, if you prefer). I think the guides then were concerned about the time, and getting everyone to move along, hurry up, we have a lot of rowing to do today.
This time down the Canyon, though, the key phrase is, "If you're hot, you're stupid." Given we're floating along a river with water not higher than 55° F, and all it takes is a quick splash to cool you down, it doesn't matter much if the outside temperature is 95+° F, there's no reason to be overheated (or even just heated).
Update: I mentioned this to Charly, about the different phrases. He said that, yes FAF is still used. He didn't realize it was an acronym, though.