Green’s Dictionary of Slang

all my eye phr.

also all his eye, (all) in my eye, all your eye, eye, my eye

[early 18C+] a phr. meaning utter, absolute nonsense; also attrib. (see cite 1927).

In phrases

all my eye and my elbow

[early 19C–1900s] nonsense.

all my eye and my grandmother

[late 19C] nonsense.