With the flick of a wrist, one couple’s dream vacation came to an abrupt end.

And it could happen to you.

In June, a husband and wife were booted from their Bali cruise after he dropped his cigarette butt overboard. The wife was allowed to finish the trip-- just alone and in tears.

Even if you haven’t touched a cigarette in ages, cruise ships come with plenty of breakable, but surprising, rules. The consequence of breaking these rules is often an immediate swift kick in the rear right down the gangway.

Here are a handful of don’ts to keep in mind next time you’re on deck.