In Finnish slang, it's used to definy a person who is living in the Northern part of Finland, usually around the city of Oulu.
kyle: wana fuck
ashley: wooow u so poro
In local slang, a definition for a person from Northern Finland, usually a Laplander.
In Estonian, a word for a stereotypical Finnish tourist, less commonly for any Finn. A person being with slow thinking, swearing, obesed and usually drunk .
Sometimes also called põder (moose), but this seems to be less offensive than poro.
After a short pause, Finns walking away, one Estonian to another: "Porod" ("Poros")