Uncle fucking Luther!

There is this guy I know he likes to go by the name Uncle Luther. This dude is really fucking annoying and I want to punch him in the fucking head. I'm not sure if he is really is nuts or if he does it to get attention. He likes to bother me and one of these days uncle Luther is really going to get it. For instance at the bar on Saturday Uncle Luther is bothering me but I'm trying to ignore him so I walk away and go for a piss and who should follow me to the pisser none other than Uncle L he wants me to high five him while I'm pissing. What the fuck is that!! I tell him to fuck off wash my hands and leave. Later he starts bugging me again this time I resort to threatening him with a upper cut. This stops the harassment for a little while but next time I run in to him It will all start again. What should I do? Should I kick his ass or just ignore him?