When I was a kid I saw for the first time a chess match in my school, they were older guys than me and every time one of them resigned knocked the king down. I thought it was part of the rules so when I started playing I did the same and never thought of it as rude.. Now I handshake my opponent!
But consider this.. even a handshake could be rude! It depends on the attitude.
How many people do this? When resigning, knocking your king down?
I think it is quite rude if this is done rougly, and disrespectful for the pieces and the game of chess.
But the thing is, I have yet to meet someone who puts his King down respectfully.
What are your thoughts on this?