First song that comes to mind that you associate with D&D. Why?
That would be Dirty Deeds Done Dirt Cheap by AC/DC. This association is fixed in my brain because one day when we were listening to it, one of my cousins remarked that this song, with the titular lyrics repeated in the chorus in Bon Scott's playfully snarling vocals, sounds like something orcs would sing as they're marching along to battle and plunder. It could also easily apply to adventurers of certain stripes.
There's a selection of other songs that, while they don't appeal much to my musical tastes, and lack even the most tenuous connection to anything D&D-ish , nonetheless remind me of D&D simply because I heard them a lot in my gaming heyday back in the late 80s through the mid-90s. That "She's Got the Look" song seemed to be playing on the mall sound system every time I went to buy new books, and if it wasn't that, it was almost certainly something by Tears For Fears. Similar stuff would be playing on the radio in the house while I sat on the couch sketching maps and thumbing through rulebooks for the perfect monster or magic item to place in the next room. It's one of those intangible things that sticks in my mind, like the New Book Smell that radiated from every brand-new rule set and sourcebook. Yep, those were the days.