Text: There are a couple of credible  The four-letter word for vagina remains off-limits in polite conversation (although that has more to do with feminism than with profanity), and the slang expression for those who engage in oral sex with males is not yet acceptable by the standards of office-meeting etiquette.
Entailment: There's a couple of credible, the four letter word for vagina is off limits in polite conversation, and the slang expression for those who engage in oral sex is not acceptable in the office.
Contradiction: There's a couple of credible, the four letter word for vagina is used regularly in polite conversation, and the slang expression for those who engage in oral sex is acceptable in the office.