A word that can take on many meanings, most often applicable when there is no word that can truly fit your emotions or what you are trying to say.
While most often used in times of stress or disappointment, merka can also be used in jubilation or in cases of extreme happiness.
"I can't find my keys...merka"
"Merka!! I just found my keys!!"
"Merka. I don't understand anything that's going on!"