Once from locking the front brake up and trying to turn/swerve at the same time. Inexperience...totally my fault.
It was my first bike and I had only owned it 4 days and was following too close and the traffic in front of me came to a sudden stop. I was not wearing proper gear either and got road rash all the way up on both arms.
Nothing like tearing up your shiny new bike with 30-day TEMP TAGS !!
This was also before they had MSF courses.
I am now a believer in the MSF course for new riders and AGATT