Post a bit of lyric. It can be simply because you feel like it, it's a favourite, you think it's silly or otherwise notable in some way, you literally just heard it and it's new to you, or whatever reason you have.
It has to be just a line or a few at most, not whole songs, with minimal or no explanation of why you're posting it, and regardless how much you want to say what it is and who it's by, don't. No artist or title (unless either are included in the bit you want to post). Those who know will know, those who want to know will look it up, everyone else won't be bothered.
Because I've recently listened to this for the first time in a LONG time and love it:
I know you know what you know
But you should know by now
That you're not me
Talk about a month of Sundays
Toffee-nosed wet weekend
As far as I can see