I'll try to answer at least part of your question.
A trigger as it relates to what guys talk about on this site is something that may send you to a bad place emotionally or psychologically. For instance, there have been men here who indicated they were triggered very badly by a certain aftershave because that was the one the perpetrator wore, and it "triggered" a flashback, a fear response, or emotional meltdown.
Also, it is appreciated if you want to mention or discuss in a post things that may be "triggering" to other users if you will put a "Trigger Warning" in the title of your post as exampled below.
What he did to me **Trigger Warning**
In response to the other part of your question about "AO" I'm afraid I don't recognize the terminology. Perhaps one of the other guys can help you out on that one or you can respond explaining what you mean.
Lots of love,