1. When you think a confrontation is near with a small group of people but a large group of people show up instead
2. Running away from a confrontation with the law
Billy just got nonged, he thought we was finna fight Fred but Fred brought a squad of 15
Bruh he just nonged the fuck out of there
in Australian slang, nong is used as a pretty mild and/or endearing insult. a bit of a twit, or idiot. nothing too mean or horrid is meant by calling someone a nong.