Green’s Dictionary of Slang

lakin n.¹

In exclamations

by our lakin! (also by laken! byr’lakin!) [lit. by our little lady]

a mild oath, euph. for by our lady!

1496		Dives and Paup. (W. de W.) II. xii. 121/2: Some [swere] by laken, some by our lady [OED].
1595		Shakespeare Midsummer Night’s Dream III i: By’rlakin, a parlous fear.
1611		Shakespeare Tempest III iii: By’r lakin, I can go no further, sir.
1822		R. Nares Gloss. (1888) I 125: by’r lakin. A familiar diminutive of by our lady, i.e., by our ladykin.
1903		Punch CXXV 9: Why, by our lakin! so they are indeed! Shall we have room to put both armies up?