Single moms: they're the hardest working people around. They raise you, put food on the table, support you every step of the way, and rarely ask for anything in return. So when you do have the chance to give a little something back, you'd better take it. When this US Marine showed up to his mom's graduation, she wasn't expecting it at all. And you'll never believe how she reacted... Watch the full video at the end of this slideshow.