A combination of the words 'slut
' and 'slapper
'. Usually used to describe a girl who will hook up with guys, stringing them along, never taking it any further.
A slat can often be a tease, dressing and acting like a slut, dancing on tables in a bar. If hit on and asked to come home by someone, a slat will get offended, physically or verbally 'slapping' them and storming off. Thus the name
That girl is such a slat, I've been trying for weeks and I still haven't got any
Guy 1: Kate is such a slut
Guy 2: Kate isn't a slut, she doesn't sleep which anyone, she just hooks up with people. She's a slat