Seattle Wave

When someone moves to the Seattle area and waves at a local and is met with a blank stare, a look away and/or a frown.

Dude 1: Jim C. was caught unawares the other day while out jogging through his new neighborhood shortly after moving to Seattle.
Dude 2: Why, what happened?
Dude 1: He waved at one of his neighbors but they returned a blank stare and looked away.

Dude 2: Oh, he got the Seattle Wave.