He demonstrated his French skills in an interview while promoting The Hangover 2, and everyone seems to be really, really impressed.
The American actor learned French while studying in Aix-en-Provence as an exchange student from Georgetown University in the '90s (thanks, Wikipedia!), which just goes to show how a) learning a second language can make you look worldly and smart, and b) studying abroad is a great way to do that. These benefits are, of course, in addition to the increased employability and cross-cultural understanding that being bi-, tri- or pan-lingual can provide.
So, here is your lesson for the day: Study abroad, learn a second language, and everyone will think you're cool! Life lessons are just so much more exciting when they come from celebrities, aren't they?