"On the 2nd day of Christmas" may be far from Mark Ruffalo's most famous movie, but it is his most festive. The "13 Going on 30" actor plays Bert, a department store guard fully committed to protecting his place of employment from petty theft — yes, Mark Ruffalo played a mall cop long before Paul Blart made it cool (via Rotten Tomatoes). When Bert catches a woman and her young niece pickpocketing just before Christmas, his boss tasks him with "keeping an eye" on the duo until their punishment can be sorted out after the holiday season. A reluctant Bert takes the pair home, learning to appreciate the joys of Christmas along the way, according to Letterboxd.
According to one audience reviewer via IMDb, "On the 2nd Day of Christmas" allows the bright green Avenger to show off his "musical talents," singing and even playing the piano in several memorable scenes throughout the movie — Mark Ruffalo's musical gifts are only the beginning of what you might not know about him. In 2013, the actor again sang onscreen, this time alongside Keira Knightley in "Begin Again."
