The term "getting it" is more of a learned way of life....like "bless you" after you sneeze. Basically this is said when you witness something amazing or extraordinary.
When someone does something like fall and make a butt out of themselves.. u say "get it"
or if you do something awesome.. you say "get it"
1.Paola is stretching with all her might before a run.
Paolo: "Get it Paola!"
2.Paolo is frantically licking a dripping ice cream cone on a hot summer day.
Paola: "Get it Paolo!"
3."Paolo, did you see those Mormans riding their bikes up that hill? They were getting it!" "Yeah Paola, They got it!"