The party hat is available today only in the coffee shop. Whack the pinata, and grab the hat when it falls to the ground.
I checked how old my penguin is today too:
Here’s me wearing the second-anniversary party hat:
I was ten months too late for the first one 
Waddle on!
Mr Snowball3
Hey snowball, i made the mission 1 video walkthrough, can you admin me?
Woo hoo! It’s funny to be admining the creator of this blog
You’ve been admined!
Mr Snowball3