from
The Collaborative International Dictionary of English v.0.48
Hankey-pankey \Han"key-pan"key\, Hankey-pank
\Han"key-pank`\(h[a^][ng]"k[y^]*p[a^][ng]"k[y^]), n. [Cf.
{Hocus-pocus}.] [Also spelled {hanky-panky}.]
1. Professional cant; the chatter of conjurers to divert
attention from their tricks; hence, jugglery. [Colloq.]
[1913 Webster]
2. Illegal or unethical behavior, usually surreptitious; as,
the boss got suspicious when profits seemed lower than
expected, and hired an investigator to see if any
hankey-pankey was going on. [Informal]
[PJC]
3. Extramarital sexual relations, especially adultery.
[Colloq.]
[PJC]