A forklift is the nuclear bomb of the 23rd Century. Only special pilots are able to use the forklift. It is obtained through an Easter egg in the game. Please do not ask us how to find it; it is a secret.
(a tip from Ambrosia: If you're destroyed after you get it, but before you land, you'll lose it. If you get it, land, and take off, it's your's until you self-destruct and use an escape pod.)