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<a href="//wordpress.org/plugins/ninja-forms/" rel="nofollow ugc">Ninja Forms</a> is a great WordPress plugin and this plugin makes it even greater!
If you’re using Ninja Forms for gathering data and one or more of textbox fields 
must be unique, this plugin is for you. The plugin is pretty straightforward to 
install, and has few settings only (language settings, basically).
Once installed, it will validate every submission to make sure the values for 
one or more fields are unique.
Brought to you by <a href="http://fineswap.com/?utm_source=wordpress&utm_medium=plugin&utm_term=readme-desc&utm_campaign=ninja-forms-unique-textbox" title="A blog and a mobile app advocating sustainability and green living" rel="nofollow ugc">Fineswap</a> Team.

Ninja Forms Unique Textbox

Extend Ninja Forms' functionality by allowing textbox field to have unique values.

Wolly aka Paolo Valenti

Jedi name:
There is a legend, George Lucas creates Jedi Name as follow: 
 Name: first 3 characters of the last name and first 2 characters of the name. 
Last name: first 2 characters of your mother maiden last name and the first 3 characters of the city where you were born.
Ninja name:
It’s a conversion found on facebook some years ago.
Mad Max name:
I found this conversion: http://paolovalenti.info/mad-max-name-generator/
Unicorn name:
as requested by Johann van der Westhuizen.

Wpit Funny Name Generator

This is a simple plugin that allow to generate your: Jedi name Ninja name Mad Max name Unicorn name

Ninja Forms Unique Textbox vs Wpit Funny Name Generator