James Franco's now-infamous Instagram selfie's been covered (see what we did there?) a lot lately and when he turned up on David Letterman last night, it naturally came up. With Letterman due to retire pretty shortly, you can see the dude just does not give a crap about being diplomatic or holding back anymore. And it's amazing to watch.

To be fair to Franco, he does give a decent explanation of where he was coming from and the reasoning behind it, but Letterman just isn't feeling it at all.

Take a look!