False, thumbless and suicide are all names that refer to the same grip, which can be used to hold a barbell when you perform free weight exercises such as the bench press. A slight change in thumb positioning changes the regular grip to a false grip. This grip does come with risks and should only be used by advanced lifters or bodybuilders who participate in bench press competitions.
False Grip Explained
With the regular grip, you wrap your thumbs and fingers around the barbell. With a false grip, you place your thumbs on the same side of the bar as your fingers. Grip the bar between your thumbs and fingers, then dig your palms into the bar as hard as you can. Wrap your thumbs and fingers around the bar in a regular grip, then pull your thumbs around to the same side of the bar as your fingers.
The false grip can be dangerous if you don't set up properly with a tight grip. The biggest concern with a false or suicide grip is that the bar can easily roll off your hands and drop onto your neck or chest, causing serious injury and even death.
In bench press competitions the barbell has a line around it toward each end, and the rules require you to have this line covered. With a regular grip, it's your index fingers that cover the lines. With a false grip, you can slide your hands wider because your thumbs can cover the lines. A wider grip shortens the distance the bar has to travel, which is an advantage in competition, notes bodybuilder Dave Tate.