Casey Affleck First Casey followed his big bro Ben into acting, and now it appears he's taking on directing as well!

Casey was in Vegas last weekend to shoot a documentary about another famous little brother: Joaquin Phoenix.

The project is supposed to be chronicling the Oscar nominated actor's transition to rap super-star, but after viewing Joaquin's performance, we're kinda hoping it's just a segment for Punk'd!

In case you missed Joaquin's stunning (and not in a good way) peformance over the weekend, we're reposting here: