Staling out comes from sales terminology, whereby a salesperson is unable to at least adequately qualify a lead to see if it was warm, cold, or worth prospecting. In this sense, a stale number, or a girl whom the PUA has kissed but not communicated with for a long time, is no longer considered “fresh” and thus becomes a stale lead.
Stale leads can still be converted, and it may be possible to rekindle some of the former attraction. But more often, stale leads require starting again from scratch. Usually it is best to feel the situation out with a low pressure method of communication such as text messages or a ping on a social networking site such as Facebook. As long as the situation doesn’t feel too awkward, it is possible to revive the stale contact.
My numbers from Halloween have gone stale by now.