A phrase originally used in the late '60s and early '70s in support of the hippie movement against the older generation's often prude and narrowminded world view, which associated long hair (especially on males) with a sloppy lifestyle. Sometimes also related to long hair on males being associated with homosexuality due to the similarity with traditionally feminine hairstyles. The phrase emphasizes that the speaker isn't affected by what is meant as an insult but actually embraces the accusation.
Lil Wayne often uses this in his lyrics. He is saying he doesn't care if a girl, chick, woman, whoever has a "bush" or long pubic hairs. He will still fuck you.
Mr.Carter-Lil Wayne
I know my role, and I play it well
And I wear it well, on my Libra scale
I suck a pussy, fuck a pussy leave it there long hair don't care
A phrase total knobs or lame ass noobs use to describe their freshly shorn locks usually while moronically gurning for selfies.
Natalia: Bin Bin, you toteel beech! You totally like ruined my new Louis Vuitton bag with your spice latte!!
Bin Bin: What evs... Short hair don't care.