We have a work area with school desks for some reason, of the crappy right-handed variety. So I notice when colleagues awkwardly try to use the desks and they're left-hand dominant.

I have a friend who is left-handed and insists on shaking hands left-handed. She will stare down anyone until they offer their left hand or do a weird fingertip shake with their right. Anyone who manages to shake her left hand without looking like a goober, she excitedly welcomes to the left handed club.