When a song is screwed, that means it's slowed down a
bit. "Chopping" is when you have the record on
one turntable, and the same record on another turntable but delayed
one beat, then you crossfade between the two for a beat to double up a half-second part. Usually you "
chop" on the fourth beat to double up the first beat of the next measure. DJs often use the "flanger" effect on one of the records to make the chops "swoop."