Where do cliches come from? My grandfather says, "You just tell a couple of jokes and you're riding the gravy train?" First of all,

Where do cliches come from? My grandfather says, "You just tell a couple of
jokes and you're riding the gravy train?"

First of all, it's hard to write jokes. Second of all, what is a gravy
train? I didn't know they were actually hauling gravy by rail.

People gather around big mounds of mashed potatoes waiting for the 5:15
gravy train to show up?
-- Rich Hall