Michael Phelps and Aquaman: adequate pop culture reference of the week

I really don't have a clue what the joke is here. I know that Sith Lord monster (AKA Michael Phelps) smoked a dube but and Aquaman is a really good swimmer (like Phelps) but but this is just weird. And why the crap bearded Aquaman? Everyone hates Aquaman with a beard. He's no Ziggy with a hat.