have a go (at someone)
1. To physically attack someone. Primarily heard in UK. Watch out for that bull in the back field—he'll have a go at you if you get too close. There were couple of drunkards having a go outside local pub last night.
2. To criticize, berate, or verbally harass someone at length and/or with great intensity. Primarily heard in UK. My wife had a go at me last night for coming home drunk again. My parents were always having a go when I was a kid—it's no wonder they got divorced.