godan verb (-su), transitive verb
Internet slang spelling of 殺す, used in casual online communication. Same meaning and usage as standard 殺す.
See also: 殺す
その発言、マジで５６すぞ。
I'll seriously kill you for that comment.
あのゲームのラスボス、強すぎて５６される。
That game's final boss is so strong it kills me.