8. Fart Explosion (MDK 2)
The glory days of cheat codes are sadly over, but while everyone loved a secret big-head mode or an unlimited ammo trick, it was the fart button from Bioware's MDK 2 that's still the biggest example of what the industry is missing by moving away from the practice.
Not only is the ability to make video game characters fart on command hilarious in and of itself, but there's another layer to this secret that makes it even more special.
In an early level you can find a large fire pit in the centre of the room, and if you fart three times near it, the space station you're on will actually explode, killing you and everyone else in the process.
The best thing about this hidden cutscene is that it's actually a secret inside a secret, and would have taken a liberal use of the first fart cheat in the first place to ever find it.