Designer: Josh Smith (@joshsmithnyc)

Why it's the worst:
It is annoying.
Without seeing it, the name alone is annoying: At least Comic Sans isn’t Comic Sanz.
It has so many signals of bad design:
It’s obvious: “Curly is fun!” “Let’s put so many curls on everything!” “and then let’s call it CURLZ”
It’s stupid: People are smarter than this. Whimsey/quirkiness don’t need dumbing down this much.
It’s not functional: Someone forgot the part about being able to read the words.
It’s overused: One of the great mysteries in life.