Muscle Group: Chest
Lie on a flat bench, your feet on the floor For balance. Use a medium-wide grip so that your forearms are perpendicular to the floor When the barbell touches your pecs. Raise the bar off the rack and hold it with your arms fully extended above you. Hold it, in this state of contraction till failure. I suggest you get a spotter for this one, if not, stop short of failure.
Variation 1: For a different feel lower the bar 2-3 inches rather than straight up and hold the peak.
Variation 2: This can be performed on an incline to hit the upper pecs, or decline to hit the lowers. You may also use dumbells.