TOO CUTE: Two sloths stole a gravity-defying kiss at the Smithsonian National Zoo. The zoo shared the clip of its sloths, Athena and Vlad, smooching in honor of Valentine's Day on Monday. br » Sign up for our newsletter KnowThis to get the biggest stories of the day delivered straight to your inbox: » Subscribe to NowThis: br For more cute animal videos, subscribe to NowThis News.