"Arra quince" (pronounced ARE-ah KEEN-say) is Spanish for "AR-15." This is a nickname for the AR-15 rifle, originally manufactured by Colt Firearms, but now made by many other manufacturers. (An AR-15 copy is called a "clone.") Parts are interchangeable between AR-15 rifles made by different manufacturers. AR-15 rifles usually shoot .223 Remington caliber cartridges (called 5.56mm cartridges in the U.S. military), but there are AR-15's chambered for a variety of other rounds as well, including .222 Remington Magnum, 7.62x39mm, 6.8mm SPC and others.
"Que tal, amigo, is that your new arra quince?"
"Si, esta bien, no? Man, I love this rifle! It rocks every bit as bad ass as that Colt your brother bought! Let's go bust some caps, no?"