How do you come up with your lyrics? Do they actually hold any meaning, or are they totally random? For example: "Jingle bells, I'm a cop"

I realize some songs may be of different nature than others, but I'm talking about the little short ones.
the origin of lyrics can be vastly different from song to song. so all i can really do is explain the example you mentioned. i guess i just figured it was an interesting surprise, because you don't usually expect the cops to show up in the 1st line of jingle bells