I find this a strange usage. I imagine it means "waiting for", "expecting". to vamp: to play a musical vamp a vamp: a short introductory musical passage often repeated several times (as in vaudeville) before a solo or between verses (Merriam-Webster) There may be further context after your sample sentence which clarifies the idea better.
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Grammar GeekI believe in this case, it means "showing off" especially in a **** manner.
Picture ladies getting all dressed up in their **** clothes and make up, walking in a seductive way, posing - they are "vamping."
The fuller context, which I've posted as Anonymous in the above, confirms, IMO, your assumptions.