I'm not a coffee drinker, but I've heard that! One of the other departments at work used to get together one Friday a month before work and get breakfast at a well-known/loved local greasy spoon...it was said that everyone wolfed their food down because this joints "signature" coffee was soon kicking in, and there were only 3 commodes back at their shop! The shop is only about two blocks away and I'm told that there was often some "drag racing" going on between the two places
That doesn't explain all the people that poop in the morning with or without coffee. Sorry for the tmi but... That said I drank a lot of Dt.Coke when I was younger. A lot. I stopped, and now it's rare crutch I use to drive after getting ready and out of the house and it triggers down there. Weird, huh!?!
We all got our "thing", now, I drink both Coffee and Tea. They both work well, especially with fruit !