The "Dressed to Skill"-Edition includes the base game as well as the following sauc(er)y extra items:

Reprobed: Skin Pack
Tuxedo, Mankini or sparkly Unicorn - 10 special skins for Crypto, the king of evil aliens himself. Fly high, with 4 special skins for his trusty saucer. Dress for the ocassion, dress for the invasion!

Reprobed: Challenge Accepted DLC
Test your skills in this post-launch DLC that adds all 4 Challenge Modes from the first instalment to Destroy All Humans! 2 - Reprobed. All modes playable in local splitscreen co-op!
Also included: numerous new Mutators that let you alter the rules of the game!

Pre-order now to get the standalone multiplayer-DLC "Destroy All Humans! - Clone Carnage" for free!