oog
It is similar to WTF without having to use the (overused) acronym.  It's more dominating because it is steaming with frustration and annoyance, not just disbelief.  The new-age version of ugh.  

Kenny G says "Ugh, my hair is caught in the car door again." while Amy Winehouse says "Oog, I think that was chalk!"

It is especially helpful to those that work in an office setting that contains a lot of Mormons, less cursing with more feeling.
"Oog, I can't believe how incompetent you are!"