When you know how to personally contact an expert in a particular field--especially when the subject is unusual, strangely specific, or
illegal. Often used when you do not want to reveal the identity of the contact or how you came to make the
acquaintance of such a
person.
Co-worker: "The boss said a
hooker took off with the USB flash drive with all our vital code stuck up her
vagina. How are we going to find her and get it back?"
You (not wanting to talk about how you did IT for a pimp/gynecologist who owes you a favor): "I know a
guy."