One of my favorite songs on my school years was Drop Dead Legs from the album "1984" of Van Halen. (It was one of the first cassette I bought).
My language is Spanish. I've always imagined that the song is about a woman who has fat legs, in the shape of a drop of liquid. This idea was confirmed after the TV series Drop Dead Diva, in which the protagonist is a large woman.
Currently I am learning English and I noticed that the word "drop" refers not only to the object (tear drop, rain drop), but also a verb related to falling, release, lower (the type of moves that would make a water drop). And when I look for the translation of "drop dead legs" I find results that are more associated to the verb, and in Spanish are incomprehensible (ex. soltar piernas muertas).
I guess then that drop dead is an idiom, but I could not find its true meaning. And what interests me most is knowing that relates to death.