This is more effective if (when you spawn in the main 'secret hideout') that you leave through the garage door exit, to the spaceship and hippie can w/ boat on top.

Now, leave and take a right past the hippie van, and down a steep hill. On the side of the wall there should be two wood panels stacked atop on another. Drive a car into it, or throw yourself at ti for a few minutes, knock them down or break them. THEN

After removing or breaking the panels, there is a hole, jump/ragdoll your way into it, then WALLAH! Your outside! You are then supplied with a vehicle, and LOTS of stuff to do. You can open the giant doors as well, to let friends with cars outside. THERE IS COOL STUFF OUT THERE, SO GO EXPLORE! Rate up if helped! :) Thanks