Okay, this one isn't so much a joke one can tell, as it is just funny.
Plus it's from a computer game.
In
Beneath a Steel Sky, you have a droid friend named Joey. There is a point in the game when Joey needs a new name, so he is given the name Ken. The main character mentions that the only Ken's he knew were dorks. Joey promises to make the name Ken synonymous with dork.
Anyone who knows Adventure games of the 80's/90's would recognize this as a reference to Ken Williams of Sierra.
Hilarious!
