What does "i'll be bound" mean?

I am certain (that something is true)

I'll be bound

intj, phrase

intj, phrase ·Rare ·Advanced level

Phrase

1
I am certain (that something is true)
"Where are those teenagers going at this time of night? Up to no good, I'll be bound!"

Intj

1
An expression of surprise. idiomatic
"Well, I'll be bound!! Another example of following the rules and being undercut on pricing by those who don't follow the regs."

"Where are those teenagers going at this time of night? Up to no good, I'll be bound!"