This is what you do to walls or floors prior to installing the studs or joist. What it means is having all the bows going the same directions on walls its not as critical as ceilings.
On ceilings all the joist should have the crown or bow up so the weight will pull them down.
Crowning refers to the direction the board "bows". If it looks like a banana while standing in your wall, you want all the bananas bowing the same way, so your wallboard will be (fairly) striaght. Although if they're that bad, a better option would be to call up the lumber yard and politely explain that they need to come get these bananas off your site, and replace them with non-bananas. Just also be aware that this happens, they, nor you, can do alot about it (to an extent). Bananas, by all means, get em outta here, but a little bit of bow or twist is nature, it happens.
On a side note, (though I know we had a big thread not too long ago that probably prompted your question) there is another forum for DIYers such as yourself to learn a great deal more than you likely will here. I don't mean to imply you aren't welcome, you most certainly are. Feel free to read anything and/or everything on here, but the other site is geared more for beginners and DIYers such as yourself, to ask questions and learn, not only from contractors, but other DIYers who have been where you are now. Hope you don't take offense to this, that was not my intent.
No offense taken at all. I am thankful for your advice and thanks much to all the replies I have a better understanding of what crowning is. I am a visual learner though so I dont wanna try to ask too many questions considering even with good answers I still wont completely get it. But dont worry I appreciate your advice and I still feel welcome, I'll still hang around here but I probably wont post alot until I learn more or have other questions or just something to talk about.
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