So if someone is bugging you with repetitious words, you can say that they are uzai. Other forms include uza and uze('e). It's a rather rude word (some people have even reportedly been killed over it), so be careful about using it. Urusai is safer, and used to the same effect: trying to get somebody to shut up.
Here's an example of usage from the latest Super Sentai* series:
*Super Sentai are the Power Rangers in the English speaking world. This series has rangers with powers based on kanji of all things. Humanity comes up with some strange and uzai stuff to entertain its kids.