run up on

"run up on" means: To confront with hostility.. This is a fairly neutral word with no inherent risk attached. There is no real cause for parental concern; it is descriptive vocabulary rather than something dangerous. If your child uses it, context will usually make the meaning clear. A brief, curious question about where they heard it is generally enough to know whether to follow up.

"run up on" means: To confront with hostility.. Register: neutral, standard English, usable in most everyday contexts. Note the regional or dialect label (AAVE) — usage may sound odd outside that variety. A common non-native mistake is to use the word in the wrong register, or to assume one fixed meaning when it is actually polysemous; always check the surrounding register and the audience before producing it yourself. In formal writing, prefer a neutral synonym or a short descriptive phrase, and use this word only when you have heard or read it being used naturally in a comparable context.