rayman,
you'd be surprised at some of the freaks that make it by the osos to ocs. a couple stories for you. i was in occ178 - fall 2001...like it was mentioned above, fall is the best time to go. on the first day of ocs, everyone is running around like idiots, stenciling things, sewing towels to their racks, making their racks, polishing their boots, ad nauseum. well this one guy next to me with a dutch boy haircut, racks out at 2200 (lights out) and i asked him if he was going to do any of the things we were supposed to do and he said, "no, i'm tired". when you encounter someone like that, stay far away, because the rounds the sgt instructors throw down on people like that have a pretty huge blast area. like jjriv said, some people just have no idea.
another story...the osos know who the dirtbags are that they are sending. they have to send "qualified" bodies. whether or not they make it...that's another story. my oso sent 5 to my class. before we left, the gunny told two of us (in private) to stay the hell away from one other guy, because he knew he wasn't gonna make it. "failure to adapt".
about ocs in general...yeah, it's hard. it's not impossible. play the game, sound off as loud as possible, haul arse like it was on fire, and they won't pick on you, even if you dork stuff up. (try not to lose your bearing too much...ha ha). believe it or not, lots of people just get hurt. that is the one thing you can't control, if you do get hurt, you suck it up as long as you can. 800mg motrin from the doc is nectar from God. good luck to you 187s.