Gilbert the Goblin's beachside vacation gets ruined by mermaids and their games in the side-splitting latest installment in The Worst! picture book series, where even the strangest of creatures can become the best of friends.

Who doesn't love a good vacation? Soaking up some sun, floating on the waves and...arm wrestling an octopus? When mermaids show up in the middle of Gilbert's goblin getaway, their fin-flapping festivities quickly turn rest and relaxation into stress and aggravation.

This is clearly proof that mermaids are the worst! Can Gilbert find his beachside bliss or will he be caught in the undertow of these seaside shenanigans?