By gum!
Definition 1 of 1
Pro Tip 1/3Regional Flavor
Mainly used in Northern England, 'by gum!' adds local color to your English and can show familiarity with British regional speech. 
By gum, your homemade pie tastes just like my gran's!
Pro Tip 2/3Archaic Charm
'By gum!' is old-fashioned, so using it can give a vintage or humorous tone to your speech. 
By gum, these old records sound fantastic!
Pro Tip 3/3Expressive Exclamation
Use 'by gum!' to express strong emotions in a mild, non-offensive way. 
By gum, I've never seen such a mess!