Final answer:
The technique of turning the LP disc counterclockwise to produce scratchy sound effects is called scratching, which is a key component of DJ practices in hip hop music.
Step-by-step explanation:
The practice you're referring to, in which DJs turn the LP disc counterclockwise to create scratchy percussive sound effects, is known as scratching. This technique became an integral part of the hip hop music culture, where the DJ uses the turntable not just for playing music but as an instrument to add to the musical landscape. Scratching is just one aspect of how hip hop music has evolved over time, with DJs and rappers from different regions contributing their own styles and influences to the genre, demonstrating the concept of stimulus diffusion.