Visitors to New York’s Grand Central Terminal are usually rushing to catch a train. But if they just paused for a moment in front of the famous Oyster Bar on the lower concourse, they would witness some very unusual behavior.

Broad shouldered financiers, Italian moms on vacation, Manhattan grandpas, tourists, locals, and even station employees all perform the same bizarre ritual. They sidle up to the arched corners of a room near the Oyster Bar, and then mush themselves face-first into the crevice like a bad child being punished. When they turn around, everyone is grinning ear to ear. They have experienced the wonder of the whispering gallery.

Each of these naughty corner talkers has an accomplice, someone standing in the opposite arch, who is their partner in acoustic mischief. Despite the noise and chaos of Grand Central the two people in the corners are able whisper sweet nothings, profane jokes, and even marriage proposals to one another.

A simple wonder, the whispering gallery works its magic every time.