by gum!
US /baɪ ɡʌm/
UK /baɪ ɡʌm/

1.
おやまあ, あらまあ
an exclamation of surprise or emphasis
:
•
By gum, that's a big fish!
おやまあ、なんて大きな魚だ!
•
Well, by gum, I never thought I'd see the day!
まあ、おやまあ、こんな日が来るとは思わなかったよ!
おやまあ, あらまあ
an exclamation of surprise or emphasis