The reason they're called the opposite sex is because every time you think you have your wife fooled — it's just the opposite!

Winchell’s quip plays on the common phrase “the opposite sex,” turning it into a joke about marital miscalculation. The humor depends on a reversal: the husband believes he has successfully deceived or outmaneuvered his wife, but reality proves “just the opposite”—she is not fooled, and he is the one mistaken. In a broader sense, the line reflects a mid-20th-century, wisecracking style of gender comedy associated with newspaper columnists and radio personalities, where marriage is framed as a contest of wits. Read today, it also illustrates period stereotypes about husbands’ scheming and wives’ intuitive perceptiveness.