Slip-cueing is a turntable-based DJ technique that consists of holding a record still while the platter rotates underneath the slipmat and releasing it at the right moment. This way the record accelerates to the right speed almost immediately, without waiting for the heavy platter to start up. Slip-cueing was introduced to the disco scene by Francis Grasso.
Francis was the first DJ to perfect the current technique for stitching records together in seamless sequences. He invented the trick of "slip-cueing"; Holding the disc with his thumb while the turntable whirled beneath insulated by a felt pad, he would locate with an earphone the best spot to make the splice, then release the next side precisely on the beat. When he got Thorens turntables with speed controls, he supplemented his cuing technique with speed changes that enabled him to match up the records perfectly in tempo
~ Goldman 1978
While the technique of slip cueing had originated in the broadcast industry several years before, it was Francis Grasso who changed the style by releasing the next song on beat, creating a continuous flow of music for a nightclub dance floor.