Green’s Dictionary of Slang

(US campus) an excl. of encouragement.

1989		Eble Campus Sl. Mar. 4: get it, girl(friend) – [...] During dance team practice, a fellow dancer may say ‘get it girl’ if you’re doing a routine or doing really well.
1996		Eble Sl. and Sociability 56: Many phrases formed around get are fixed expressions that show [...] encouragement (get it, get some).