Boys How to Train Your Dragon Pajama Set. Let your dreams take flight in these awesome How to Train Your Dragon Pajamas! The blue long sleeve pajama top features a large colourful print of Hiccup and Toothless and 'The Hidden World' logo below. Paired with long black bottoms which also showcase the film's logo and feature elasticated waist and cuffs for ultimate comfort, these PJs are sure to stir the thirst for adventure in your little viking!