Today's new word

Shu'up[shə-əp]: an all purpose negation that, while obviously being a contraction of the phrase "shut up", is quite closely related to the phrase "nu uh". Pronounced with the same cadence and whiny inflection as the latter phrase, it also is used in precisely the same way. Interestingly, while that phrase is primarily used by children, with adults using it only in response to them or as part of an attempt at humor, this word can be used bypeople in their mid to late twenties amongst each other without there being any detectable trace of irony.

However, it still sounds (to an outside observer) like a 5 year-old who isn't getting their way.