Depends. If you're walking on a track and pass someone, yup. If you're in a mall, then nope. All about frequency.
eg if you're tramping in the wop wop's you stop and have a great big chat.
Same goes with bikers I guess. If everyone rode bikes, no one would wave
. But when you haven't seen a rider in an hour I give them a air "High Five" (Borat voice). Kidding. But you know what I mean.
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