When I was in New York, everyone said they were "standing on line" instead of "standing in line." Haven't lived there for almost four years now and I still can't shake that one. Also, at fast food, "to stay or go?" instead of "for here or to go?"
I haven't really been in PA long enough to pick up any of the Dutch slang, but there are a few Philly words that shouldn't ever be exported:
Jawn - Literally, any noun. "Did you see that red jawn they sell at the jawn?"
Drawlin' - Kind of like "tripping," used to describe someone who's bugging out.
Earf - Weed or murder, depending. Ones comes out of the Earth, the other involves putting someone in it.
Bull - Any male.
Chinese store - Any corner store run by any type of Asian.
Papi's - Any corner store run by anyone of Latin decent.
Those are the big ones. I have run into the "MAC machine" question frequently.
Ever since I moved out of Ohio people look at me like I'm a hillbilly when I forget and say "ain't" or "dang."
When I lived in Lexington, KY, people used to make a point and say "you all" for the plural of you. Like they were afraid absolutely no one would understand them if they just said "you," but wanted to make sure people knew they weren't the type of Southerner who said "y'all." Also, this one is super regional, but it used to drive me INSANE--there was a fairly major street called Versailles, but instead of pronouncing it like the French, they said every single letter. Ver-sales. Ugh.
Also, Louisville cannot be correctly pronounced by anyone who has not lived in the South their entire life. Properly done it has somewhere between ten and eleven vowels.