Four lettered words at our house

...are not allowed.  We've been pretty good at narrowing our "curse" words down to ones involving five letters, like "Seren" and, more recently, "Penny." 

However, we have recently discovered that a four letter word has been in use around our house for the last 6 months or so.  The tone of this word may change depending on the situation.  Whenever there is a rotten smell, we say the word.  Whenever, valuable stuff gets knocked over, we say the word.  Whenever there is fur on something that was clean, we say the word.  Whenever my back or head is used as a stepping stool, I say the word.  Whenever we are trying to sleep and we are woken up time and again, we say the word.  We say this word the moment we are clearing the dishes from the dinnertable.  Finally, we say this word when his fuzzy, fluffy tail and behind makes it's way to sitting upon one of our heads,"EARL!!!"

Yes, the word is none other than the name of our gray cat, Earl.