1) Euphemism for a penis, where "one-eyed" refers to the external urethral orifice (or pee-hole) located at the tip of the penis' head.
2) One-eyed willy, both alternate spelling and definition.
Expression's origins: derived from the name popular character from the film "Goonies" (although this context has been permutated with time). See also dong, dick, schlong, willy, wang, johnson, cock.
I have six beers, and next thing I know, I'm staring into the eye of Jake's one-eyed willie.
An urban legend about a one armed man that roams the woods at night giving unsuspecting victims one armed handjobs. Known mainly in the upper peninsula of Michigan, more specifically in the keewenaw peninsula in the county of Baraga (named after William Baraga aka one armed willy).
One armedwilly snuck up on me in the woods and boy am I sore
A bald boi who can fucking kill anyone and anything in one punch. He's so powerful in fact, that there's never a single moment when he's at his limit or uses his full power.