"ONG" stands for "On God" and is used to emphasize the truth of a statement or to show strong agreement with something. It is often used interchangeably with phrases like "I swear to God" or "hand to God". For example, someone might say "Sour Patch Kids are the best sweets ONG" to express their strong agreement with that statement. The acronym is commonly used on social media platforms like TikTok, Snapchat, and texting.