Twin spin    Before electronic looping of beats or “samples” or
even turntable scratching existed, DJs had to repeat
instrumental breaks from songs manually so that the same few
bars would play uninterrupted. In the earliest days of hip-hop,
DJ Hollywood and Grandmaster Flash figured out how to do so —
and pioneered a house party DJ technique — by buying two vinyl
copies of the same song so you could find the groove in one
record while the other finished playing