A person who can run a mile under 5 minutes (usually referring to on a track). This person, if male, is pretty cool. However, if a girl can run sub 5 for a mile then they are basically the coolest person in the world. Imagine maintaining one minute and 14 seconds in the blistering sun for four freakin laps around a boring, oval track. Yeah, we are just THAT cool.
Dude, that sub 5 miler is a boss! Yeah, and her Nike Zoom Victories are sick!!!!!