A term used mostly by gay men to depict something unpleasant, foul, or undesirable. Often replaces words such as stupid, dumb, gay, etc. Ugh, this is so vaginal, I have to work a 9 hour shift today! Those pants are straight up vaginal.
Warning signs such as fear and/or nervousness around other dogs, displays of aggression only under certain circumstances (while on leash, in the presence of food, in the presence of the owner, etc.), or most commonly, over-the-top play behavior can be seen at any stage of the dog's development.
The fallacy of stating that dogs who raise hackles are aggressive is counterproductive, as it labels dogs through mere speculation and assumptions. If you are uncertain as to why your dog may raise his hackles, consult with a veterinary behaviorist.