限时秒杀

限时 = "time-limited"; 秒杀 literally "second-kill" - Chinese gamer slang for "kill in one second" (instantly), repurposed by e-commerce to mean "sells out in seconds". Quintessential 双十一 (Double 11) and 618 mechanic. Top items often sell out in single-digit seconds, requiring users to mash refresh - a dedicated sport called 抢购 ("rush-buy").

秒杀 alone works as both noun and verb: 这款手机被秒杀了 (this phone got snapped up instantly). The 限时 prefix emphasizes the sale window. Compare 限量 (limited quantity, no time limit).