Threatining...

Guests should "ensure their clothing and accessories are respectful to fellow guests," reads Carnival's website FAQ.

That means nothing worn during the cruise should "contain any message that may be considered offensive or contain nudity, profanity, sexual innuendo/suggestions. 

In addition, clothing/accessories should not promote negative ethnic or racial, commentary, or hatred or violence in any form."

While Carnival's crew isn't "the clothing or expression police," spokesman Vance Gulliksen says the change came after some reports in other travel sectors of customers wearing clothing with "very threatening messages."

So enjoy the cruise and please keep your thoughts/hate at land.  Just a thought.