What is the meaning of "Olha a Pedra"?

I’ve been following a few brazilian music artists lately and something they seem to say on social media is “Olha a Pedra”.

I translated it using google translate and it said it means “Look at the Stone”, but that doesn’t mean anything significant without context in the USA. Does it mean something different in Brazil? Is it something cultural that I don’t understand?

Some usage examples:

• https://soundcloud.com/ergyrge8greh/olha-a-pedra
  (the music artist who owns this account is fairly well known and recently encrypted the song titles on this archival account, but the URL still has the song name. this is more of a novelty thing almost. comments on his main songs on youtube contain the phrase ‘Olha a Pedra’ as well, but I don’t want to disclose the artist’s name for his sake. I also want to note that he makes all other songs on that account private BUT Olha a Pedra right before he releases a song on his main alias)
• https://www.youtube.com/watch?v=cb7lRInEa6c&t=19
  The DJ introduces a song with a call “olha a pedra!”

those are the two main examples, but a quick youtube search shows several results that have lots of views.