When a guy sits down in a seat and spreads his legs apart wide, as if his testicles were hot as lava and needed ventilation. Usually used pejoratively, especially against men who do this on public transit and so waste space or make their seat neighbors uncomfortable.
Ugh, I was on the T and this guy say down right next to me and was lavaballing halfway onto my seat! Rude and gross!
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.