For some reason, to me when I see DTW, I will mentally pronounce it as either Det-wahh (the french pronounciation of Detroit), or Metro. No reason why which one comes up at whichever time.
MCO will forever be pronounced in my head as "O-I-A" due to the local media's insistence on referring to it as OIA in any story they ever do that mentions the airport. (It's not even "Orlando International", it's always OIA)