Oi!

"Oi!" is a British informal exclamation used to get someone's attention or express surprise, annoyance, or emphasis. It functions much like saying "Hey!" or "Hey there!" and is often directed at someone nearby. The term is common in UK English, especially among working-class speech, and can be used playfully or irritably depending on tone and context. While simple, it effectively conveys a need to alert or react, making it a versatile interjection in everyday conversation.