Well, if you know the song Smells Like Teen Spirit, there's that part right at the beginning where it goes "dum da dum... whack-a whack-a dum dum, dum da dum... whack-a whack-a dum dum"

The first "dum da dum" is an F power chord on the E string (1st fret), and the "whack-a whack-a" is the "xxxxxx" and you mute the strings by resting your hand over the strings and don't press down and simultaneously pick the strings pretty firmly. Then, play a B flat power chord.

Repeat with the G sharp and the C sharp power chords.

Hope that helped!


p.s. It don't matter if you play electric or acoustic, the "whack-a whack-a" sounds the same.