The wagging of the index finger of your dominant hand in a very stern and disapproving manner. This is done to show your disapproval of the (usually idiotic) actions of another. Note that the wagging must be done so slowly as to make it a very awkward situation.
Usually accompanied by the Look of Judgement
Mr. English Teacher: What are you doing on the floor?
It's a combination of looking unsure and a disapproving look. It's a combination of " what are you talking about" look and the look of disapproval. It's the safety net. It's like letting them know that if you knew what they were saying and that it would offend you, you would disapprove. It only appies if what they were saying would offend you. If they said something that will not offend you if you knew what they were saying, the look of questionable disapproval would not apply. It's used online, although rarely. It's the name of the emoticon below.
Idiot: Haven't I seen you in www.eatyoursoup.com
Hot Japanese girl with feelings: (has no idea what the idiot meant).
Hot Japanese girl with feelings: F***! I should've used the look of questionable disapproval!
A disapproval boner is what old, judgmental people get when they see something sexualized that was produced for the consumption of a younger audience. Clearly a sign of intense self-loathing.
As defined by Jon Stewart on the Daily Show 5/1/14, referencing Bill O'Reilly's condemnation of Beyonce's sexualized videos.
"Bill O'Reilly probably ran that sexy Beyonce B-roll in order to bring some much-needed disapproval boners to his aging audience."
The sound you hear from at least 5 people in a room when you say something that crosses the line. Everybody says "AWWWWWWWW", and because there are so many people in the room who disapprove it is like surround sound, Dolby style.
*Somebody makes a joke*
*Someone else makes a joke, but it is too dirty/wrong/offensive*