To refrain from flirting with or making sexual advances toward someone in order to maintain an atmosphere of propriety no matter how attractive or suggestive the object of your lust is (i.e., boss' daughter, receptionist/mistress of your top client, MILF of your best friend or girlfriend, etc.). Sexual self control.
On the way to a sales call:
Salesman: "Harry, wait till you see the jugs on the receptionist at Acme."
Sales Manager: "Now, hold on you hornball. If you blow another deal like last time - banging the buyer's wife ..."
Salesman: "...I didn't know she was married!"
Sales Manager: "I'm just saying, we can't afford another screwup, so just holster your dick."