One week ago, I was on a MD80 in 5B. Two ladies get on, each carrying a tall cup of coffee, seated in 4A and 5A. While Y is still boarding, 4A places her coffee in the center section, and accidently topples it over onto the gentleman sitting in 4B. My seatmate, 4A bumped her coffee once, but luckily it didn't spill over.

I don't believe hot drinks should be prohibited, but please exercise caution when bringing along those hot drinks!