There are, of course, other ways to accomplish this. I was "scared straight" as a young teen when my mother cancelled her plans for the evening so she could go talk with my teachers after school about my behavior, which wasn't severe enough to warrant suspension but was nevertheless bad enough to disturb my parents and teachers.

Ideally the kid is set back on a good path before their behavior becomes severe enough to warrant suspension, but sometimes (probably most often because of poor parenting) this doesn't happen.