Brits and Americans have hundreds of different phrases for the same thing. Luckily it's usually a source of amusement rather than frustration. A flashlight by any other name is still a torch. My personal favourite is 'fairy lights ' which we boringly refer to as 'Christmas lights.'
I don't believe that anybody has come to a conclusion on why something is funny. It's funny because it's ridiculous and it's ridiculous for different reasons at different times.