You can get special options by completing certain tasks:

Laser Sight Ammo: Beat Mission 4
Jetpack: Beat Mission 8
Fast Walk: Beat Mission 13
Invisiblity: Beat Mission 16
Low Gravity: Beat Mission 20
Industructable Landscapes: Beat Mission 25
Banana Bomb Upgrade: Beat the last mission
Aqua Sheep: Get Gold on The Super Sheep Training
More Powerful Longbow: Get Gold on the Euthanasia Training
Enhanced Shotgun: Get Gold on the Rifle Range
Enhanced Grenade: Get Gold on the Artilery Range
Blood: Get Gold on Basic Training
Sheep Heaven(Which makes all crates Sheeps): Get Gold on Crazy Crates
Industructable Landscapes: Get Elite on Deathmatch
Full Wormage: You need to Complete, all Training, Elite on Death Match, a
nd Complete all Missions.