The Slap Nixel acts exactly like a regular Nixel. He finds humor in harming others, sometimes even in his fellow Nixels.
The Slap Nixel is simply a square-topped Nixel with a machine. Strapped at the back of the Nixel is a grey, square machine with blue highlights, and two slender, black arms connected to two large ball joints and smaller ball joints for elbows. In the arms' hands are two blue flyswatters with a grid pattern, and a blue holder with a thicker blue handle at the bottom. On the square mechanic is a grey zipper.
Slap Nixels were encountered as enemies during Nixel swarm battles with Mixels who have escaped from capture.
Later on, a standard Nixel is standing on his machine with a wrench, fixing it. It suddenly sparks out electricity and smacks the mechanic Nixel with one of the swatters. The Slap Nixel laughs, but then reacts in shock when another jolt activates the other swatter and hits him, as he gives out a moan of pain. ("Calling All Mixels")
- He appears to be the strongest and largest weaponized Nixel.