Two common senses: (1) 三甲医院 — the highest tier (三级甲等) in China's hospital rating system; (2) 进入三甲 — generally "reach the top three" in any ranking/competition.
history
Originally from the imperial examination system (科举): the top three passers of the palace exam (殿试) were named 状元, 榜眼, 探花, collectively the 三甲. The modern hospital grading co-opted the prestige term.
