why yesterday's poetry worm was "dig and be dug in return"

I've liked this for ages: "Motto" by Langston's Hughes I play it cool I dig all jive That's the reason I stay alive My motto As I live and learn Is dig and be dug in return Yesterday, while doing minor landscaping and gardening, the last line kept going through my head. After a couple of hours, I wondered why. Then I looked at the shovel in my hand. My subconscious has a really stupid