Pick Slides
A pick slide (also known as a pick scrape) is a relatively simple technique, where you slide an edge of the pick along the strings, generally from the bridge towards the neck. It creates a noisy sound that descends in pitch, which is often used to introduce distorted guitars in an arrangement. It is typically performed on the thicker, wound strings, where scraping the pick against each winding creates a very raspy sound. The left hand mutes the strings while performing the slide to prevent any string resonance and focus the sound on the noisier slide.
It can also be used on unwound strings to get a similar sound as a slide, but with less sustain. Here it is often moved back and forth across different strings and from bridge to nut, creating a sound of quickly played random high notes that don't necessarily even fall in the chromatic scale for the instrument's tuning.