Whatever McDonalds worker
More commonly abbreviated to wmw, this is used to show that you think the person you are talking to is so low in soceity (a mcdonalds worker) their opinion doesn't matter. Most commonly used at a secondary school level. Can also be used with a hand gesture making a W with both your thumbs and index fingers, then turning it upside down for an M and then back up for a W.
Scabby person: Did you know that jackie fancies you?
Ben: Whatever McDonalds worker