Mad Hatter Day is a great day to be silly and celebrate silliness. 

The Mad Hatter is a fictional cartoon character depicted in Alice's Adventures in Wonderland. The Mad Hatter is always acting silly. So, on Mad Hatter Day, it is only fair and fitting to act a little silly yourself. 
Despite being a silly day, the selection of the date was actually quite logical. The Mad Hatter wears a top hat. On the front of the hat is a slip of paper with '10/6' written on it. The paper is believed to be an order to make the hat, and that it costs ten shillings sixpence. 

We have prepared a few words on this topic   #Mad_Hatter_Day 

? Mad |mæd|- безумный. 
? Silly |ˈsɪli|- неразумный, глупый,легкомысленный. 
? Fictional |ˈfɪkʃənl|- вымышленный, выдуманный 
? Top hat |tɑːp| |hæt|- цилиндр 
? Sixpence |ˈsɪkspəns|- сумма в 6 пенсов