Pitfall of Privity

Bro, I've seen many of you guys struggle with this one - 'Privity of Contract'. Our notes say it's about the relationship between contracting parties but it's so much more than that. Can anyone give me a real-life example of how privity works in contract law? Like, in a scenario where a third person is affected by a contract between two parties? Maybe some case law to back it up, bhai? I'm not looking for textbook answers, something that happens in real life.