Boktai: The Sun Is In Your Hands : Metal Gear Solid 4 Guns Of The Patriots Cheats

There is a gun called the "Stun Gun" which is actually a reference to one of Hideo Kojima's older games, Boktai: The Sun Is In Your Hands for the Gameboy Advance. This is confirmed when Solid Snake raises the gun towards the sun to recharge and yells out "Sunlight", much as the main character did in Boktai.