Ummion
Somebody who says "um" a lot, or many times in a row without using actual complete thoughts into a reply.
Kevin: Wanna go to the mall?
Grace: um...
Kevin: do you??
Grace: um...
Kevin: Gosh stop being such an ummion!
Grace: um...
Kevin: do you??
Grace: um...
Kevin: Gosh stop being such an ummion!