Journeyman Project 3: Legacy of Time had a lot of easter eggs, some of which poked fun at the developers, but others were just odd. You almost always had to hold the E key in order to find them.
If you warped to Shangri-La, then held E and moved forward, there would be a random can of Mountain Dew sitting on a pedestal behind you.
There was also a part in the game where if you mouthed off to Genghis Khan, he would punch you out. There was a steam vent behind him in his tent; if you climbed up from there and hung around for too long, he would backfist you down into the tunnel. Got that? Good.
So there's also a part in El Dorado where you look down a well-type thing to see your final objective. If you had already gotten punched out by Khan, you could hold E as you looked down. Your character would fall into the hole, get propelled through a bunch of fiery caves, come out the steam vent, get backfisted, and then fall back through the world and back up the hole. Trippy.