What do they call Dwayne "the Rock" Johnson's son? The Pebble.
The Rock's Son
Explanation
Explain Bear
Listen up, buttercup. Dwayne "The Rock" Johnson is a big, strong dude, right? Like a rock. So, if he had a son, instead of being a big rock, he'd be a little one, like a pebble! See? It's funny because it's small!