Sometimes, it's a rhyme or a rhythm that triggers them.
For example, out in the garden I mentally put off a task and the word "procrastination" flashed like a miniature lightning bolt in my mind. In milliseconds Carly Simon's melody for "Anticipation" responded.
next thing I knew, I was humming:
is just a delay,
is keeping me waiting ...
Other times, it's a response to a current situation.
It happens to me a lot. We start on a road trip, and I'm humming "On the Road Again."
Feeling irritated, I'll go with "All you need is love..."
Yesterday, the pest control manager, while crawling around the basement to find the extent of active termites, also discovered a water leak. So we had to call the plumber too! When he finished, and was paid I surveyed the mess left behind.
What sprang to mind?
You're taking one down,
You sing a sad song just to turn it around ...
You had a bad day.
You had a bad day."
What are you singing today?