Houdini Hancock

Refers to where you sign your name to a document with disappearing ink, either because you don't want to actually be held to whatever contract/agreement that you've scribbled your signature on, or you fear that the person who's asking you to sign said document is merely trying to take advantage of you or trap you into something unreasonable/illegal, and so you're just trying to protect yourself from getting dragged into something you shouldn't be involved with.

I always insist that a contract-singer use a pen that I supply him with, so that I don't hafta worry about any Houdini Hancocks.