Halloween costume for work ideas?

at work we're celebrating halloween a day early... so we're all dressing up tomorrow (thursday) I thought i was going to have something ready, but unfortunately i cant find my box of halloween costumes... so i have to just go with something that i have... I do have a few dresses, nothing fancy... but a plain black dress, i thought about going and getting a witches hat/ broom, and some black panty hose... and go as a witch with it...other than that, my closet pretty much consists of normal, t-shirts, jeans, and work clothes (slacks and shirts) - i did think about going as Pam on the office (i am a receptionist..) but i don't know exactly what to do as far as making sure that people know that im trying to be her. ... but i just need any other ideas... im planning on running up to Party city and trying to find something really quick this evening... but not sure.. anyways, please any ideas would be helpful... oh, and remember i'll be wearing this all day tomorrow.(9 hours) .. at work, sitting in my chair. Thank you!