Step 1: Change your computers date to the 15th of december 2011
Step 2: Open left 4 dead. Go to your settings and enable the developers console, than type: map c1m1_hotel versus
Step 3: Once you've entered the map you can need to spawn as survivors! if you spawned as infected no problem, exit the map and repeat step 2! Step 4: Find some special infected and kill them, if you are lucky they will drop a present. You need atleast 3 presents to get the achievement. Be fast! after a few minutes you will get kicked because you are the only player in the match!
Step 5: Get the achievement! This took me about 30 minutes to do and was pretty simple.
Thanks for reading my guide! This is my first guide that i ever made so leave me some tips on what i can improve on my further guides. If you need help with it add me on steam and send me a message :)