Oho, yes! I second that. Also very fun on other drugs. *cough*triggrhappy94 said:You Don't Know Jack.
You will lose your mind.
I also recommend any GTA as mentioned here, none of them require much time before you can freeroam and GTA titles always have fun cheats to abuse. Or you could just download a savefile since you're on a PC and unlock everything that way.
You'll need some friends for this one, but pictionary is super fun drunk.
EDIT:
Amazon.com has a discount running on steam codes for all GTA titles (among tons of others) until the 31.
(Just make sure you select "PC Download - Steam DRM" if you want a steam key.
The "PC Download" option doesnt give you a steam key afaik.)
Vice City [http://www.amazon.com/Grand-Theft-Auto-Vice-Online/dp/B008FPV5IS/ref=pd_sim_vg_1]
San Andreas [http://www.amazon.com/Grand-Theft-Auto-Andreas-Online/dp/B008FPV4N4/ref=pd_sim_vg_2]
GTA IV [http://www.amazon.com/Grand-Theft-Auto-Online-Game/dp/B008FPV6CS/ref=pd_sim_vg_1]
Episodes from Liberty City [http://www.amazon.com/Grand-Theft-Auto-Episodes-Download/dp/B00A9XQ890/ref=pd_sim_vg_4]
GTA IV+Episodes from Liberty City [http://www.amazon.com/Grand-Theft-Auto-IV-Complete/dp/B00906A1HM/ref=pd_cp_vg_2] (Cheaper if you want both of them.)