Should the Explainer dress as a sexy Neytiri this Halloween? Or maybe go for something classic, like a naughty nurse? No, wait, maybe a slutty French maid? Halloween provides an excellent opportunity for young women, and also men, and also not-so-young women, to go out in very little clothing. When did sexy costumes become the norm?
In the 1970s. Costuming has been a part of Halloween since at least the 19th century, when Scottish and Irish children went “guising” house-to-house on in exchange for coins.
Full Story When did Halloween get so tawdry? – Slate