German slang for "Let's go inside!" because it sounds like "geh' mer rein" which is coll. for "gehen wir rein!".
Used by the same people who say "wayne!".
Cool guy1: "Ey voll kalt hier, lass ma reingehen."
Cool guy2: "Jo, Gamer Ryan!"
which is:
Cool guy1: "It's gettin cold, let's go in."
Cool guy2: "Yeah, let's go inside!"
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