Gene-slammed refers to any person or creature/dinosaur that has had their DNA altered somehow by technological apparatuses designed by the Dark Slam Gods. The phrase "gene-slammed" was coined by Gene "God Hand" Gene, also known as Gene, also known as BIG SLAMMU, to describe what had happened to him and his brothers (Rip, Shred, and Gorge), but the term can also be attached to any of the other victims of the Dark Slam Gods. Gene-slamming is how the Dark Slam Gods created an army of monsters to aid in their battle against the Neo Slam Gods.

The technology for gene-slamming is almost perfect, except for the fact that those who have been gene-slammed become completely terrible at everything. Monsters are often subjected to the Mega Chamber, a device in Bastion of Final Hell that makes the subject a hundred times larger. Bubberu is one example among hundreds of both mutational processes.

In an oft-recounted tale, Shadowslam and co. created a monster by gene-slamming one of Gene's brothers, Shred, with a Killer Killer Whale, and renaming him Whammerhead (a categorical error on the part of the Dark Slam Gods, but one that ultimately mattered little). Shadowslam's plan was to send Whammerhead back in time to destroy the Neo Slam Gods' ancestors, using a time machine called the Time Slammer. However, Shadowslam forgot that the Neo Slam Gods had no ancestors. When Whammerhead appeared in the designated time and place, he was immediately crushed by Neo Slam Gods, albeit ones who were several thousand years younger.

Prior to its modern usage, "gene-slammed" referred to the state of being slammed by Gene, hinting at a lack of creativity on Gene's part when he redefined the term.