Bean, I'm guessing that most people have a certain degree of chain-of-association going at all times, and sometimes we make subjective connections which no one else could discern from the objective subjects. Usually, though, I don't mention the endpoints of the chain and don't articulate the associations, but just let the mental dialogue continue internally. It's hard though, because sometimes I lose track of what's occurring in the conversation I'm supposed to be in, and then I'm thought vague or absentminded. It's genius I tell you! Genius!

Like you, I have a tendency to recall songs associated -- by time, place, subject or some other factor -- with events and conversations then occurring. My stepmom used to be amazed (and a bit annoyed) at how I was always humming or singing a line from a song, in apparently random succession, because I was always being reminded of songs by the things she was saying. She's gotten used to it now ...

Having a conversation with my autistic son is especially challenging, since he lacks the vocabulary to articulate what he wishes to convey, and will attempt to communicate his thoughts with associations he has made which don't necessarily comport with associations anybody else would make. Sometimes, it's like playing Chinese charades (I speak no Chinese).