This is the bowl one smokes to bring himself back down to what is called "public high" after smoking out of an instrument of mass destruction, such as a waterfall bong. This ties in as well with the warm up bowl, the one that gets you ready for the instrument of mass destruction.
"damn, man, I gotta go meet up with my parents"- Guy 1
"no worries man, we'll just cool you off with a warm-down bowl."- Guy 2