Warney's cry is a modified version of the tactical nuke from Call of Duty: Modern Warfare 2.
Warney is a playful jab at 4chan's jannies and mods. Its Pokédex entry ("They do this for free.") is most likely a reference to a common insult towards 4chan's jannies ("He does it for free!"), and its species is literally the Janitor Pokémon.
The shiny form's sign color matches up with warning colors for driving signs, red being usually categorized with other warning colors.
Warney is a combination of "Warn" and the suffix -ey. It may also be a shortening of "Warning".