Mixing vodka with beer? Is it safe to mix small quantity of vodka with beer.

Any there any dare devils who had tried cocktails on their beer?
In (Soviet) Russia it is called Yorsch ("yorsh" means ruffe, a small fish remarkable for its hard and sharp spines). 

There is a variations of it – "From brown bear to the polar and back". You take a glass of beer, drink a little, fill it up with vodka, drink again, fill up again and keep drinking and filling until the mixture is colorless. After that you keep on drinking but start to fill it up with beer. It is said that many have seen The White Polar Bear but only few have managed to see The Brown again.