IMHO - In My Humble Opinion
Incall - You meet the girl at their place.
Independent or Indie - An escort who works on her own, without an agency affiliation. The escort manages her own calls, bookings, advertising and finances.
Interpreter - Condom (e.g. She spoke French without the aid of an interpreter = BBBJ)
IPO - Initial public offering: used to denote the public introduction of a new provider, usually via a review.
ISO - In Search Of
Italian - Penis rubbing between butt cheeks
Jack Shack - Refers to an establishment (massage parlor, lingerie modeling) that is not usually full service. You should expect only massage (usually nude or topless) and a hand job, but more services might be available.
Jimmy Hat - A condom
John - A man who patronizes prostitutes