Causes Isaac to dash a short distance. If Isaac runs into an enemy while dashing, he picks them up and a crosshair spawns under him that can be controlled with tear controls. After one second, Isaac leaps up and slams down with the enemy, dealing 50 damage to them and any enemies he lands on and creates circular rock waves that damage nearby enemies and destroy obstacles.
Isaac is immune to damage for the duration of the effect, which allows him to use it to get into curse rooms and travel over spikes without taking damage.
In addition to normal enemies, Isaac is able to suplex:
Stone Grimace type enemies, although they will move back to their original position (requires multiple attempts as it may not always work)
Fires (including Fire Places; if Isaac suplexes a fireplace, it will glitch out and leave an invisible damaging fireplace where he lands)
Using this on immobile enemies and bosses such as Mega Maw will result in Isaac and the enemy returning to the original location of the enemy after hitting the ground
Enemies that are normally invincible, such as the ghost of Blighted Ovum (which deals no damage to it) and The Haunt before it moves to the top of the room.
Tainted ???'s poops, making it easier to break tinted rocks and open secret rooms. After being suplexed, the broken poop sprite can be repeatedly suplexed as well.
Panic Button: As long as Suplex! is fully charged, Panic Button automatically triggers when about to take damage, avoiding the damage and potentially grabbing an enemy in the process. Allows Isaac to grab an enemy by simply walking into them, provided the item is charged.
It also likely refers to the Suplex ability from Final Fantasy, which is itself somewhat of an internet meme due to it being possible to suplex ridiculous things like trains or the suplexer themselves (when under the confusion status).
Several games in the Kirby series also feature a functionally identical Suplex ability. Suplex's pickup graphic resembles the ability's icon in Kirby Super Star.
Using Suplex! in combination with Mega Mush makes you grab enemies and move them around until you leave the room. Doing this on any of the Ultra Harbingers or The Beast will make the enemy disappear and render you unable to move at all.
Entering or leaving the berserk state induced by Tainted Samson, Soul of Samson or Berserk! while holding an enemy using Suplex! causes the enemy to be instantly killed, no matter what. If it is a boss, the boss music will still play even after the boss' death. Certain enemies may not spawn items when killed this way (Uriel/Gabriel will not spawn Key Piece 1/Key Piece 2)
Using this on both stages of Dogma will softlock the game.