Broken down, "pissed-up" means inebriated or
drunk. A "
slapper" is, well, a slut. Or, a
woman of loose morals. So, a "pissed up slapper" is also known as a drunken trollop or whore.
"Lets go to the bar tonight and pick up a couple of pissed up slappers." "Check that pissed up
slapper going down on Mark in the
corner." "It's a sure thing cause she's a pissed up
slapper."