We all get them, some all the time, some rarely. An earworm is a tune or lyrics that just pops into your head (because you've heard it before), and won't go away, dominates some or all of your conscious mind.
Today, my earworm is "Seven Spanish Angels", which has to be the saddest song ever written.
"She reached down and picked the gun up
That lay smokin' in his hand
She said, "Father, please forgive me
I can't make it without my man"
And she knew the gun was empty
And she knew she couldn't win
But her final prayer was answered
When the rifles fired again
Read more: Willie Nelson - Seven Spanish Angels Lyrics | MetroLyrics
Some days, your eyes just need washing...