USAF Surplus Airmen Battle Uniform Pants - ABU

ABU, just like ACU, is actually a nomenclature for the type of uniform -- but has since become synonymous with the pattern of camouflage, the Air Force's Digital Tiger Stripe.

The ABU (uniform) is a slightly different cut from the Army Combat Uniform, with the chief difference being the sizing convention and the very considerate stretch built into the waist of the ABU.  Perhaps they weren't optimistic about their long term force readiness and fitness outcomes.

Either way, ABU is the hipster version of UCP camo, so you can wear this and pretentiously correct people who misgender your drip.