Was sagt der Fisch?

You need to have a trusted account. Only gifts that are purchased on trusted accounts can be traded immediately; otherwise there is a 30-day cool down before the gift can be traded. Any account that has made any valid purchase from the Steam Store more than 30 days ago is considered trusted.

How it works:

Step 1: You trade the deposit vs the 4-pack.
Step 2: You activate the game on your account.
Step 3: You get 3 extra copies in your inventory.
Step 4: You trade back the 3 copies vs the deposit minus the price of the activated copy.