Obnoxious behavior refers to behavior that is highly objectionable or offensive. It can also refer to behavior that is annoying or objectionable due to being a show-off or attracting undue attention to oneself. Obnoxious behavior can also refer to a person who is unjustly disagreeable, argumentative or objectionable; brazenly rude. In archaic usage, obnoxious can also mean exposed or vulnerable to something, especially harm or injury. ^{dictionary.com 1 2}