. >> steve castillo is also serving time in the shu, convicted in 1987 for first-degree murder, his sentence35 years to life. >> i think probably the main thing is staying busy. trying to find something positive to do. people start getting that rage, and before you know it, they start disrespecting each other and it gets ugly. i've seen a guy sitting down playing chess all by himself with chess pieces made out of his own feces. guys walking back and forth, just pacing the cell butt naked. we get these little small plastic state-issued cups. they'll sit and bang on the sink hours on end. all day, all night. as if they've just totally lost their mind. >> some of us are stronger than others. i think that's what pelican bay is about. only the strong ones are the ones are going to make it, you know? this is it right here. everybody hears about pelican bay. but when it comes to doing time here? nobody wants to be here, you know? >>> next on "lockup" -- the hidden messages and secret codes gangs use to communicate inside and outside pelican bay. >>> well, everybody has hopes. they want to touch the