A shot made by a player near the basket in which a player starts at one side of the rim, then shoots the ball underhand at the other side of the rim. The player may perform this shot by reaching over the other side of the rim from underneath or jumping from one side of the rim to the other and shooting the ball when the player's back is facing the hoop. It is often referred to as a "reverse". A dunk using the same maneuver is called a "reverse dunk".
The idea behind a reverse lay-up is that a player can use the rim to protect the ball from shot blockers. This is a considerably athletic maneuver since a player either needs great wingspan or a long hang time to perform the shot. Players who aren't as athletically gifted or blessed with long limbs can compensate by playing the ball off the backboard with the proper english. Reverse lay-ups are commonly accomplished when a player is attacking baseline, but the more acrobatic players can pull off this shot from any angle.
The most memorable reverse lay-up in the history of the NBA was performed by former Philadelphia 76ers small forward Julius Erving, when he was facing the Los Angeles Lakers in Game 4 of the 1980 NBA Finals. Dr. J started off from behind the backboard, palming the ball with his right hand, then carried himself to the other side of the rim to flip in the legendary reverse.