The average person in Ireland refers to them as knackers these days. They were previously known as tinkers.
They are inbred due to a mistrust of settled people.
They are always looking for a way to make easy money, the same as every other common thug.
In years past that would have meant stealing lead or tarp.
These days it usually means robbing the elderly or selling poor quality drugs.
The Pikeys stole Tommy's mothers TV when he brought her to mass.