I got a bottle of Martinelli's and I'm dumping
It on anybody that's kicking it in the grotto

Meaning

In big celebrations, it’s customary to pop a bottle of bubbly and spray it all around.

(thats $300 Dom Perignon they are spraying btw)

But obviously since Mack is sober living, he has the best apple juice known to man, Martinelli’s

To help improve the meaning of these lyrics, visit "Castle" by Macklemore and Ryan Lewis (Ft. Macklemore) Lyrics and leave a comment on the lyrics box