Pennsylvania Contemporary A Cappella League (CAL) group KeyStone has taken a risk here with Frosty the Snowman: it's generally a kids' song, and KeyStone's "thumpety-thump-thump" rhythm is infectious to the point of becoming an earworm.

Luckily though, the risks pay off: this recording is impeccable, and the song's relatively simple arrangement is spruced up with little one-liner asides that beg for repeat listens. (Seriously, you'll hear new witty comments every time.) Here are the things that really jumped out for me: a rich solo that's just the right level of perky, backs that are engaged and energetic without overpowering the lead, a one-line solid bass solo that doesn't sound like an afterthought, a Harry Potter reference, and an awesome trumpet melody in the bridge(!). This song won't have an infinite shelf life — holiday songs never do — but it doesn't need to. It works well both as an upbeat holiday song and as an introduction to KeyStone's sound.