The story
Deverbal from smack down (“to defeat utterly and decisively, especially in a humiliating way”), from smack (“sharp blow, slap”, noun) + down. Influenced by earlier throwdown. Popularized by: * the United States professional wrestling television programme WWF SmackDown! (first broadcast on April 29, 1999), now called WWE SmackDown and produced by World Wrestling Entertainment; and * the phrase lay (or put) the smack down (“to start a fight”).
Etymology from Wiktionary, CC BY-SA 4.0.