what does the capital CPT mean in straight outta compton?

In “Straight Outta Compton,” CPT means Compton —the city in California that N.W.A. is from. The phrase “capital C-P-T” is just a stylized way of saying Compton.

Quick meaning

• CPT = Compton. It’s shorthand used in rap and street slang for the city.

• In the lyric, “capital C-P-T” emphasizes pride in being from Compton.

Why it’s written that way

• Rap lyrics often use abbreviations for place names and identity.
• “Capital” here is more of a vocal emphasis than a formal acronym meaning.

TL;DR

“CPT” in that song means Compton.