I don't know. We just made it up based on the fact that "Testify" was derived from the word "testicle" and then we just changed it to nad.
Ha ha, Nadify, it's like testify only different.
by The Bag Boy May 13, 2005
To confirm, concur or corroborate. Normally accompanied by a confident jerk of the the neck.
Mr Lee, can you please nadify that statement?
by Street Rod November 08, 2005