You might recognize Cory Williams from his baby food taste test pregnancy surprise that went viral last month, the rock skipping video he made last year, or some of his other work on YouTube.
When you skip a rock over a frozen lake (with ice of the right thickness), it makes an incredible sound due to flexural waves. Luckily for those of us who don't have tons of frozen lakes nearby (or the ability to skip rocks), this guy filmed the phenomenon. If you want to skip his intro and hear just the rocks, head to 40 seconds in.