BASE Jumping

An extreme sport in which a parachute or a wingsuit and a parachute are used to land safely after a jump from a fixed object. "BASE" is an acronym that indicates the four categories of fixed objects from which one can jump: Building, Antenna, Span, and Earth. 

Chaz Villette used to engage in BASE-jumping when he was younger. He had at least one friend who died in the activity. He took it up again (legally, this time!) in the DVD extra "Bridge Day."