(used self-deprecatingly, e.g. when asked to sing a song) to put one's artistic incompetence on display
Definitions (CC-CANTO)
humbly stating "making a fool of oneself" before a show or an act
Definitions (粵典–words.hk)
動詞
表演時展露自己嘅弱點，多數作為謙詞 (hum.) (of one's own performance) to show oneself up; to show one's weakness or incompetence
獻醜不如藏拙
献丑不如藏拙
better to conceal one's weakness then to show oneself up
大家咁俾面要我唱歌，噉我就獻醜嘞！
大家咁俾面要我唱歌，噉我就献丑嘞！
daai6 gaa1 gam3 bei2 min2 jiu3 ngo5 coeng3 go1, gam2 ngo5 zau6 hin3 cau2 laak3! As all of you do me the honour to sing, I'll show my immature skill.
Definitions (Wiktionary)
verb, humble
to show oneself up; to show one's incompetence or inadequacy (speaking of one's performances)
Definitions (Kaifangcidian)
（沒有對應漢語詞彙）
Examples (粵典–words.hk)
Cantonese
献丑
獻醜
hin3 cau2
(hum.) (of one's own performance) to show oneself up; to show one's weakness or incompetence
Cantonese
献丑不如藏拙
獻醜不如藏拙
better to conceal one's weakness then to show oneself up
It's better to conceal one's weakness and not to show oneself up.