The away message you get on instant messaging services like AIM when your friend is eating his girlfriend.
Guy 1: Hey Guy 2, what's up?
-Auto Response from Guy 2- Out To Lunch.
Guy 1: Again...?
not paying attention/ dazed off
"You're out to lunch"
a) A sign that is put on the outside of a business premesis that is indicating that it is temporarily non functional, and that business will resume within the hour.
b) not paying attention.
Out to lunch, back at one.
He's out to lunch.
Drunk, intoxicated, plastered, wasted, etc.
"My friend was out to lunch when he jumped off the roof."
Techincally speaking, when a piece of network equipment goes down.
"The server just went out-to-lunch; what a piece of shit."
Going OUT of the room and meeting your co-worker in the closet, TO LUNCH down on her sweet spot.
I love taking Angela OUT TO LUNCH, I could eat all day long with her.
something your supervisor usually is.
Hey man, have you seen the sup lately?
No man I think he's out to lunch!
He's out to lunch period.