I'm guessing that should read "Bear"?
Play the secret mission ("Revelation") set at the church. If you have one of the DLCs installed (CW I think) the marker appears without having to visit the police station, so not so secret.
Play the mission until you and Julius have to go outside and APCs turn up. Let Julius die, jump in the Bear and take it to your garage. Customize to taste and use it to give the pimps a real surprise when playing "Snatch"