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All the time (all my life, almost) that I lived in southern California I only heard "chones" for underwear.
I always check first but in case you are in this situation as we speak and are using your blackberry to ask I would say if your wearing chones use those otherwise use your socks.
Never was, never can be … and the poor saps who continue to fight me on this will never figure it out: if said object (in this case, film) was created with the sole purpose of making a dude take his ween out of his chones and pull it hard til it erupts, then it ain't art.