I was up all night with a sick friend

I was up all night with a sick friend.

an unlikely, but popular excuse for not being where one was supposed to be the night before. Bill: Where in the world were you last night? Mary: Well, I was up all night with a sick friend. Mr. Franklin said rather sheepishly, "Would you believe I was up with a sick friend?"
See also: all, friend, night, sick, up