The act of unwittingly dialing one's own cell phone, often keeping an open line and allowing the unintended call recipient an amusing eavesdrop session.
Sally (via text): Hey, did you just try to call me?
Joe (via text): No.
Joe checks call log, then (via text): Oh, snap! I just accidendialed you! How much of the past 20 minutes did you hear??
"Sarah must have accidialed Erica, because Erica does not even like her. If that was not an accidial, then she better loose Erica's number if she knows whats good for her!"
"I was trying to call Kelly A. but I accidialed and called Kelly B."
It is said of the situation where a person has the bad luck to make contact with his testicles against an undefined surface or object, intentioned or not.
Given the nature of the word, it is more appropriate to design cases where the interaction is made with a moving object, for example, a ball.
Although it is extremely painful for the victim, it tends to be considerably funny to people who witness it.
Today in the baseball game the pitcher took a nutshot; the baseball hit him in the nuts.
Man, I just watched the funniest nutshot video ever.