Guy's Behavior

Weird question but why would a man keep banging/nudging into you as he walks past you?

This guy is my boss at work.
Anytime I’m just standing about for example waiting to use the photocopier he will walk behind me and nudge me and if I turn round he just keeps walking and he doesn’t laugh or anything like he was being funny he just walks on like he didn’t just about knock me over.

Today I was standing waiting to talk to another colleague and there was plenty room behind me and he made me stumble because he walked right into me.

Someone even mentioned it to me today asking why he did that.

It’s really weird. When we talk to each other he’s pretty normal and doesn’t ever mention it like he’s doing it as a joke or something.
Weird question but why would a man keep banging/nudging into you as he walks past you?
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