A variant of 实锤 (solid proof, 2014-ish Weibo slang) — same pronunciation, but 石 ('stone') visually upgrades the 锤 ('hammer') into an even heavier, more unimpeachable instrument. Treat them as interchangeable online.
register
Exclusively internet / gossip register. Formal Chinese would use 确凿证据 or 铁证 instead. Heavy on Weibo scandal threads, 知乎 drama, and K-pop / C-pop fan arguments.
