Im rather new to TTT and me and my friends own a server that plays it, im rather fond of the maps however that have secret doors and buttons that you press and crazy stuff happens, ive noticed these mostly on maps made by "Redcow"

There is one secret i know exists in one of his maps ttt_concentration there is a way of making a cow to appear that plays music, how would i go about setting this off?

And could you also name other maps which have these kind of features?