Here's the sign posted near just about every elevator in the country:
"In case of fire use stairs"
Is it just me or does that sentence mean something different than it's supposed to mean? The intended warning is actually:
"In THE case of fire use stairs."
In my polluted mind there is a big difference between "in case of" and "in the case of". Every time I read one of these signs I interpret it to mean I should NEVER use the elevator because while I am on the elevator there might be a fire. A similar sentence might be "In case of rain bring an umbrella." The implication isn't that you should only bring an umbrella if it is already raining but that you should bring your umbrella no matter what, IN CASE it rains.
Now, according to dictionary.com, "in case of" means "if there should happen to be," which would point towards the "in case of fire" interpretation, and NOT the "in case of rain" interpretation. Right? "If there should happen to be a fire use the stairs," makes sense. "If there should happen to be rain bring an umbrella," also makes sense, but it isn't making the sense originally intended. My rain sentence should be "In case it rains..." and NOT "In case of rain..."
It turns out I was wrong and all those signs warning me to take the stairs in case of fire are correct. Way to go elevator sign makers!

Jeff,
Forgive me, but I have another approach: What the signs are actually telling you is to use the stairs within the "Case of Fire". Case, of course, being the noun referring to your building. Duh!
That took me a minute to decipher but has won my heart. Next time I am caught in a "case of fire" I will use the stairs.