Skilamalink sounds like a word someone made up on the spot. That may be roughly what happened.

J. Redding Ware recorded it in Passing English of the Victorian Era (1909) as Low London slang, and gave it a definition that fits its slippery sound: Secret, shady, doubtful. A deal that is skilamalink is one you would not want to look at too closely. A person who is skilamalink is probably up to something.

Then Ware adds a sentence about where it came from, and it points to the stage. If not brought in by Robson, he writes, it was re-introduced by him at the Olympic Theatre, and in a burlesque.

Robson was Frederick Robson, one of the great comic actors of mid-Victorian London. His years of real fame began at the Olympic Theatre in 1853, where he made his name in burlesques — comic send-ups of serious plays, including a Macbeth and a Medea. Ware is not sure whether Robson coined skilamalink or picked it up from the street and gave it a bigger audience, and he says so.

That honesty is worth noticing. Slang often reaches the record through a performer: someone on stage says a word with enough relish, the audience carries it home, and a lexicographer later notes that it came from the theatre. Ware could only say which theatre, and which man.

Where Robson got it, if he got it from anywhere, nobody knows. The word itself has no obvious parts, which is part of its charm. It does not describe shadiness so much as sound like it — a word that slides sideways out of the room.