A term used to describe how fast you are driving when you are running well over the legal speed limit.
Mark and Todd were running Mach Nine on Highway 12 while they were wipping kittys and downing Coors light!

Mike and Bobby had to rip it up to Mach Nine to out run the County Mounty on the back way to the lake the other night to go drag racing!
by Freckman February 2, 2007
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