South Park: The Stick of Truth - Inside Joke Achievement

**This is a Missable Achievement **
Achievement - Inside Joke
While inside Mr. Slave, you summoned Mr. Slave.

First, you must acquire the Mr. Slave summon. Go to the post office, and in the back behind the counter you'll find Mr. Slave's package. Return it to him at his house and you'll unlock his summon. NOTE that you can only use him once per day, so make sure not to use him on the third day (the day that starts with the Underpants Gnomes). During a battle inside Mr. Slave, use his summon to unlock the achievement immediately.