Below, check out a clip that's being billed as "rare footage" of Eddie Van Halen making elephant and horse sounds with his guitar backstage at a venue, pre-concert. I mean, how "rare" can it be if you're watching it right now?
In its most basic form, the lick is a sequence of six notes played as a sextuplet or two sets of triplets (depending on the tempo). The notes are played on the same string, which makes it very easy to alternate-pick and build speed. Once you have mastered the basic pattern, you can apply the lick to different scales and positions to give an almost endless amount of variations.