Freebasing is taking a drug through vaporization or inhalation (ie, smoking), and usually refers to pure heroine or crack cocaine. So in effect, I read that line as "He's going to take drugs and jump off the building, thinking he can fly."<br/><br/>Of course, what he<em>meant</em>was he's going to jump off the top of a building with a parachute... but that's not what I originally saw!