My favorite has to be that indignant “I’m in here!”
Well , DUH!! :rolleyes:
My post was inspired by lieu’s recent bathroom experience.
"I unleashed the hounds".
Man that was classic!
Quasi
Personally, I’m fond of the version as currently displayed in kambuckta’s location 'neath her name. 
Usually, I’m too shocked to say more than an eloquent “Heyyyyyyyyy!”. Usually, that’s all that is required.
I usually ask in a polite voice, “Did you want something? Or just coming to soak in my all-natural fumes?”
come in?
I usually just close my legs and cover up what can’t be concealed by my thighs, then assume an embarrased look on my face. Words are trivial compared to the power of the Get Out Of Here face.
I have a phrase I use in all situations that seem to warrant it:
AM I FUCKING INVISIBLE?
I did this to someone else at a bbq at a doper’s house last weekend. The poor guy just turned bright red. Me, I just smiled and said “Nice seeing ya!” before I quickly shut the door.
There’s always the tried and true “do you mind?”
how about “Did you bring snacks?”
or “Come on in- the water’s fine!”
I actually had the presence of mind once to say: “Pardon me if I don’t get up.”