"Unpleasant, no, why dear your armpits are unpleasant. Unbirthdays are very pleasant indeed. It is an event that is typically celebrated on any of the 364 or 365 days in which it is not your birthday. This is not to be confused with your half-birthday." 

He threw a gloved finger in the air, "wait a minute!. I know, I know, I know!!! We should throw AN UNBIRTHDAY PARTY!!!!" He announced with glee.That's when the Dormouse climbed out of one of Hatter's sleeves and sleepily shouted "An unbirthday party!!!!" he said with both eyes closed and pointing a lazy finger in the air.

"Of course we will need to organize this, we'll need a band, chairs, bouncers, clocks, butter, cake..." 

"CAKE!!!!" the Dormouse cried

"SHUSH, seriously I can't hear myself think when you shout in my ear. Now where was I, oh yes, cake, and flamingos, and music, and dancing, watermelons, and jam, tea, lots and lots of tea, and tables, a DJ, and lots of lights and colors, also fun is a must! Fun fun fun FUN!" 

"FUN!!!" the Dormouse agreed.