Leave it to Jimmy Fallon [1] to get Kristen Stewart [2] to open up about her many facial expressions [3]. During Kristen's stop by The Tonight Show on Tuesday, the actress joked about how she actually does smile a lot. As for why the cover woman is often striking superserious yet sexy poses in magazines, including the August issue of Marie Claire [4], Kristen suggests she's just going with the flow. Watch her hilarious chat with Jimmy in the video, above, and don't miss all the fun they had while playing "Word Blurt." [5]