Obnoxious behavior can be defined as actions or attitudes that are highly unpleasant, offensive, or annoying to others. It’s the kind of conduct that makes you want to roll your eyes, plug your ears, or simply walk away. Think of it as the social equivalent of nails on a chalkboard – it grates on your nerves and tests your patience.

highly objectionable or offensive; odious: obnoxious behavior.

extremely unpleasant or irritating. A skunk gives off an obnoxious odor to defend itself. We were tired of the obnoxious behavior of these spoiled children. It is obnoxious of you to keep interrupting.

very unpleasant or rude: Some of his colleagues say that he's loud and obnoxious. When she's in a bad mood she's obnoxious to everyone.

Psychologists hesitate to use the term because it has no theoretical basis. Terms like that label a person, not a behavior. For our purposes here, however, we will consider any person or behavior "obnoxious" when it is deliberately offensive and makes others feel uncomfortable.