Sammy Hagar Grateful Dead Jam

Weir and Hart joined the former Van Halen singer on Saturday night during a holiday benefit concert hosted by Hagar.

The boys, along with Sammy's band The Wabos, jammed out to "The Weight" by The Band and "Rainy Day Women #12 & 35" by Bob Dylan. Weir is often a guest at Hagar's annual charity show, held this year at 142 Throckmorton Theatre in Mill Valley, California.