It's a large fire that people party around. Depends on who's doing it. If they're g rated they roast marshmallows and hot dogs and sit around and talk. If its more R rated they have loud music,get drunk,dance,ect. Basically it's a big fire for gatherings.
It is a large outdoor fire held in good spirit. Usually shaped like a pyramid and stacked very high with logs and wood pallets and set a blaze. It is usually an event held in celebration of a change of season, or a homecoming or just a gathering of friends and classmates with plenty of camaraderie, singing ,dancing and drinking to accompany it. Popular with college kids.
It's a social event that occurs around a large campfire. Where I'm from, it's a REALLY large fire. The fire department is usually on standby, no kidding. Many universities will hold these events during football season to celebrate homecoming and other events during the fall.