Head to Tweek's place and find him in the back room. Talk to him to receive your new task of getting the delivery from Kenny's place.
Leave the shop and go to Kenny's place in the southeast corner of the map. After talking to her mom, you'll get the garage key so open the McCormick garage. Once inside the meth lab, talk to one of the meth heads there to deliver the letter. You'll have to defeat them in battle afterward.
After defeating them, remove the obstacles so you can access the ladder leading to the attic. You'll find Kenny's Bloody Club there. You can also get a Wife Beater from the chest behind the stove. Get Tweek's package in a paper bag sitting on a shelf near the door. Deliver the package to Tweek to complete the task. He'll be added as your friend and you'll get his stash key. Loot the chest in this room then report to Cartman.
Back in the Keep, Cartman will teach you, Dragonshout. A quest to bust Craig out of detention will become available. Kenny will be unlocked as a buddy as well.