There's a pilot on YX that insists that all coffee carried on be either consumed or securely stowed before takeoff. Can't hold it in your hand or tuck it in your seat pocket; it must be stowed somehow in one of your carryons, securely. The FAs insist that it's the pilot's requirement.

I've had this pilot on my regular flights between BOS and MKE more than once, so it wasn't just a fluke. One of the other regulars on these flight refers to him as the "Coffee Nazi."