If this is right, it's way over the line.
A report claims that Kyle Busch -- and his family -- endured some heckling and worse during his race Wednesday at Kalamazoo Speedway. Check out this account, with claims that Busch was subject to chants wishing he'd die, his family was caught on the heckling and little kids were booed for saying his name.
Now, there's a reason Busch is known as Rowdy. He goes on tweet storms even against fans. His on-track language can be, on a good day, profane, and he's not afraid to anger fellow drivers with his criticism. He's often described as the most despised driver in NASCAR.
Given all of that, it's OK to boo him. Taking it to his family is clearly over the line.