A woman who "slaps on" tons of make-up, usually spotted by that. Tons of make-up will surely hide the ming underneath form the session before.Usually goes out pantyless, and is totally brainless, homes for thick wallets and loud mouths.
Alternatively, slapper could refer to the slapping sound during intercourse or a slapping sound the labia make when she walks.
God look at that slapper! She has more paint than the Mona Lisa!!