“What do you call a retired miner?”/“Doug.”

A miner riddle is:
 
Q: What do you call a retired miner?
A: Doug (dug).
 
The joke was posted on Reddit—Dadjokes on March 4, 2019.
 
       
Reddit—Dadjokes
Posted by u/TheWhiskaz March 4, 2019
What do you call a retired miner?
Doug.
 
Twitter
Dad Jokes
@Dadsaysjokes
What do you call a retired miner?
Doug.
6:54 PM · Mar 4, 2019·Twitter for iPhone
       
Twitter
Dad Jokes by dadbot
@dadbot2000
What do you call a retired miner? Doug. https://ift.tt/2Tpnwud
9:06 PM · Mar 4, 2019·IFTTT
 
Twitter
Ben Rainbow flagWolf face
@BenjiTheFurry
What do you call a retired miner?
Doug.
2:46 PM · Nov 20, 2019·Twitter for iPhone
 
Twitter
Dad Jokes
@Dadsaysjokes
What do you call a retired miner?
Doug.
3:15 PM · Feb 26, 2020·Twitter for iPhone
 
Reddit—Jokes
Posted by u/Seeyalaterelevator February 27, 2020
What do you call a retired miner?
Doug