the lowest grade of "H" in Hong Kong Certificate of Education Examination (HKCEE)
Definitions (粵典–words.hk)
動詞、舊式、香港
即係考試唔合格；以前嘅會考評級一共分為A至H八級，其中G同H都屬於唔合格，"H" 嘅形狀就好似一堂梯咁，所以考到H級就叫擔梯；後來G同H級合併做U級，呢個講法亦都漸漸少人用 to fail in an examination; literally: to carry the ladder; a reference to the lowest grade back then, "H" which sort of looks like a ladder