i'll swan
What does i'll swan mean?
A polite Mid-South stand-in for 'I swear,' used the way Yankees would say 'I declare' or 'well I never.' Common with older Memphis and Appalachian speakers who didn't want to take the Lord's name in vain. Heard as an exclamation of surprise more than an actual oath.
Origin
Likely an Anglo-Scottish dialect contraction of 'I shall warrant ye' (>> 'I s'wan ye'), brought south by Scots-Irish settlers. Documented in American dialect literature from the 1800s onward.