In the UK it's not gonna get you anymore than a slap on the wrist but it also makes the person that receives one look utterly fucking pathetic. Also making these fascists look like utterly pathetic weaklings is one of the better ways to deal with them.
It also cuts short whatever they're doing and makes them fuck off. You want an event with a fascist over with? Milkshake. They need to take a shower now. They're gonna leave.