Slang for a Puerto Rican. Used because they often go for the $2 box cutter rather than a more expensive butterfly or switchblade. I was told this by a Puerto Rican himself, so I assume its legit.
A pair of pants, shorts, or any other article of clothingcovering the "box" that is too small or tight and is shoved so far in her vag it looks like her box was cut.