Here's how to do it SAFELY ...
ALWAYS use either a Smith Machine with a SPOTTER . IMPORTANT: NEVER, NEVER, NEVER
ATTEMPT TO USE A REGULAR STRAIGHT BAR, EVEN WITH A SPOTTER AND WHEN YOU USE THE
SMITH MACHINE, ALWAYS, ALWAYS, ALWAYS USE A SPOTTER!!!
A spotter should be someone you KNOW understands how to "spot" someone,
preferably someone you've worked out with before.
If you don't have a spotter, use a set of DUMBBELLS to be safe.
Keep the amount of weight much LOWER than usual until you learn how to perform the
movement properly.
On a FLAT bench (the exercise is actually LESS effective using an incline bench),
with a MEDIUM grip, and starting from the "up" position, SLOWLY lower
the bar (or dumbbells) to neck level, keeping your elbows pointing out AWAY from
the body.
Focusing on contracting your chest muscles, raise the bar/dumbbells as quickly as
safely possible back to the start position.
Perform 3 sets of 8-15 reps.
By REALLY hitting these hard to reach areas and ALSO calling upon the larger areas
of your chest to perform this movement, you can stimulate MANY more muscle fibers
resulting in explosive growth for the entire chest region.
Give it a try, be safe, and oh yeah, one more warning...
This one's gonna make you hurt the next day!