In one of the country's most iconic rock n roll clubs in the country, LA's Rainbow Room .. on one of the country's most iconic rock n roll streets - the Sunset Strip - one of the country's greatest rock n roll stars, Dave Grohl - did one of the most rock n roll things ever when paying his tab ... 

Yep, after playing a surprise pop up show in the venue's parking lot to promote his Cal Jam Festival (video below) - Dave went into the bar for some drinks and ran up a $333.30 bar tab  ... so naturally, he left a 100% tip - bringing the total bill to $666 ! 

Here's some footage of  the pop up show :