My nephew is still into Frozen after we saw it last week. We were watching some of the Olaf clips on my phone yesterday (which his baby brother seemed to really like), but then my nephew said, "I like the part that goes 'Let it go, let it go..." He actually sang that part about 4 times, since those are the only lyrics he knows.
So I asked if he wanted to watch that part. He said yes, so we put the Let It Go scene on, and the two of us ended up singing along to the whole thing. I do know all of the words, however, neither of us can really sing, although that didn't stop him from trying to hit all the high parts.
Then he asked if we could do it again, so we did. It was so funny!