Raiders of the lost Ark

Go to the flying saucer mesa with the Chai and parachute (latter optional.) Walk off the mesa and drop the Chai when you start falling. The _Yar_ will appear at the top of the screen.

With a sufficiently high score (which will include the above) puts "HSW2" in your inventory when you finish the game. ("HSW" = Howard Scott Warshaw, the game's author "2" indicates his second game.)