Palm muting
From Riff Wiki
Rest the edge of the picking hand on the strings right at the bridge while picking. Closer to the bridge = less mute; further up = more thud. Mark it PM in tab.
PM . . . . . . . A|-2-2-2-2-2-2-2-2-| E|-0-0-0-0-0-0-0-0-|
Combine with the last note unmuted for the classic "chug chug chug RING".