Pinched Harmonic

From GuitarWiki

A Harmonic that you play while Fretting and that requires the string to be hit by both the Pick and the thumb that holds the Pick. You must place your thumb lower on the Pick to accomplish this, and the thumb must hit the string immediately after. It also helps if you Pick the string approximately halfway between the note Fretted and the Bridge.

This can also be achieved someone sloppily by newer players by holding the pick with the thumb, and hitting the string with your index(pointer) finger. Pinched Harmonics can be better heard with high gain and volume.