I know it when I hear it.
Then I proceed to immerse myself in the song until I can sing all the words.
Sometimes it can take me all summer.
In the past I have memorised such songs as You Can Call me Al by Paul Simon.
It's The End of the World As We Know It (and I feel fine) by REM.
We Didn't Start the Fire by Billy Joel.
Loose Lips by Kimya Dawson (of the Moldy Peaches) The longer version than the Juno soundtrack (the one with the Anti Bush/Iraq war lines in it)
So here is this summer's song. Drumroll please.
Want It Back by Amanda Palmer and the Grand Theft Orchestra.
If you are squeamish about nudity then go to youtube and search for the "clean" version (I hate that term. it implies the human body is dirty) which had pixelated wobbly squares over her bits.
Do you sing in the summer? What do you like to do to challenge yourself?