420 Miles Per Hour Share definition Flag When you're blazed as fuck and you only do things at your own speed. "sorry i'm late bro, i had a joint before I left, now i'm going at 420 miles per hour" 420 Miles Per Hour by isitallovermyface March 3, 2017 0 0 Get merch Get the 420 Miles Per Hour mug. Buy Now — $32.95 See more merch