I'm confident you solved it, John, but I've never heard that phrase "Big D" before. Another cryptic clue to confirm, please.
I believe the words to the song go something like: Big D little a double L as
Also, for those of you that have traveled to Texas there is only one "Big D".
I've been to Texas. Except for Austin, yeah, seems like one big "dump" for the most part. Sorry, Texicans, that was just too easy to pass up from California.
This tragedy will be in the news a lot in a couple weeks, 50 years. [Edit: Nobody caught this? What a goofy mistake from an engineer. It's going to be 51 yrs this year. It was a historical error, not a math error.]