Green’s Dictionary of Slang

(US campus) a picnic held in the woods where students can drink, play around, neck etc.

1966		Current Sl. I:3 1/2: Boon-docker, n. A beer party in the country.
1983		N. Proffitt Gardens of Stone (1985) 119: They had their boondocker, taking a keg of beer, their old blankets [...] to some dry desert river bed.
1997–2000		College Sl. Research Project (Cal. State Poly. Uni., Pomona) 🌐 Docker (boondocker) (noun) A keg party located in the desert or a similar remote area.