Does everyone here remember when Will Ferrell was an elf in the movie Elf? When he visited The Late Show this week for St. Patrick’s Day, he was dressed like a different familiar tiny being, a leprechaun. Although at first glance, you might think Ferrell just loves playing mythical creatures who he’s far too big to convincingly play, in this case, he dressed up as a way to teach David Letterman’s television audience about the true origin of St. Patrick’s Day. Here he is singing about it:

Ferrell also stayed dressed up as a leprechaun to talk about SNL40 and one of the biggest sourpusses in the audience.