It's safe for work (usually), just silly kid nonsense

https://en.wikipedia.org/wiki/YouTube_Poop

Examples:

https://youtu.be/XyuHSjXo2Nk

https://youtu.be/wUmretPQAHo

https://youtu.be/JD3L9h45fOs

https://youtu.be/Hn0QvVgmMaQ