This page explains in detail the interactions between the Donkey Kong series and the Gravity Falls series.
Gravity Falls episode Fight Fighters
September 14, 2012
The tenth episode of Gravity Falls is about a videogame character called Rumble McSkirmish coming to life to fight for Dipper against Robbie, and in a scene they get to "Barrel and Crates Incorporated", where Rumble stars throwing barrels at Robbie in the same style as the titular ape in Donkey Kong, in an enviroment similar to the 25m stage, with a background music reminiscent of the Donkey Kong music. Robbie even jumps over barrels with a sound similar to the jumping sound from the game, and scores 200 points for each barrel. Note that in hte original game each barrel is only worth 100 points.
License
The creators of Gravity Falls held no right over Nintendo's Donkey Kong, but they only included a minor reference to the game.