This was a project I made in a little over 4 hours, from idea to finished implementation, and finally purchasing the domain and setting up the hosting on S3 (since it's entirely static).
I guess sad smiley isn't very explanatory. It happens when there are either no consonants or no vowels selected. It's a dead simple algorithm that alternates between the two.
I should have it ensure at least one vowel or consonant is provided when clicking randomize, or give a popup.
Could you enhance the character slider to allow a user specified "recipe"? Like a setting for the ratio of of vowels to consonants?
That might reduce the occurance of 'yy' like results.
Completely pointless, but it was fun to make.