I'll be a monkey's uncle!
US /aɪl bi ə ˈmʌŋ.kiz ˈʌŋ.kl̩/
UK /aɪl bi ə ˈmʌŋ.kiz ˈʌŋ.kl̩/

1.
我真是太惊讶了, 真是活见鬼了
an exclamation of surprise, disbelief, or astonishment
:
•
You won the lottery? Well, I'll be a monkey's uncle!
你中彩票了?哇,我真是太惊讶了!
•
He actually finished the marathon. I'll be a monkey's uncle!
他竟然跑完了马拉松。我真是太惊讶了!