(adj) means annoying in a particularly vulgar and cheeky way. To be rude, insulting, and offensive. It is often used to refer to something intentionally oversized or intentionally offensively loud. Bragging is considered obnoxious, as is intentionally disregarding a rule. Showing off your disregard for a rule or order. Being blatantly disrespectful of social norms and those who would enforce them.

Who fucking knows anymore? First, it meant factual, and now it means fictional. What the fuck, internet... what the fuck?

People who are overly loud, sometimes offensive, & almost always irritating; will give you the compulsion to tear your own ears off to shove them down their throat.

the kind of people u wanna shoot in the head..

Annoying; Pesky; Pain in the neck; Bothersome

annoying/demanding

–adjective
1. highly objectionable or offensive; odious: obnoxious behavior.
2. annoying or objectionable due to being a showoff or attracting undue attention to oneself: an obnoxious little brat.
3. Archaic. exposed or liable to harm, evil, or anything objectionable.
4. Obsolete. liable to punishment or censure; reprehensible.