The word 'shlogpper' comes from to words: Slut and Whopper.
It is an offensive term used insult a female who is a whopper (fat) and a slut too.
It is not to be used directly rather indirectly. e.g. If a 'shlogpper' is walking across the playground and you are not alone you would yell inconspicuously 'awwwwww shlogpper' and the people you are with will find it rather funny.
Use directly at your own will.
Paul: Awwwwww shlogpper!