I guess this is a running Tonight Show gag, wherein Fallon imagines he can go up against the likes of Robert Downey Jr. in a wordless expressive act-off. GTFO, Fallon; you’re clearly out of your league.
It’s a pretty silly gag, but as usual, RDJ gives it his all. Now, if only he’d definitively communicate Iron Man 4’s fate.
When asked if Downey had ever worked with his The Judge co-star Robert Duvall before, the actor amusingly related that he had…but apparently Duvall didn’t find it (or ever meeting RDJ) a memorable experience: