Rima Himelstein, M.D., of the Crozer-Keystone Health System, wrote this for the "Healthy Kids" blog on Philly.com.

I must admit, hazing has me puzzled. I know it's a humiliating or dangerous activity that is expected of a student who wants to belong to a group. I also know that three local high school teams - two in Pennsylvania and one in New Jersey - have made headlines recently for hazing. But why would revered athletes throw it all away and engage in hazing? Is it because they were hazed when they were younger? Maybe. But there must be more to it.

These three schools are just the tip of the iceberg. Almost half of high school students involved in organizations reported being hazed. Even more shocking, 25 percent said their first hazing experience occurred before age 13.

Hazing is not limited to boys on sports teams. The research found that all students involved in high school organizations - from sports to theater to social to scholastic groups - were at risk.

Not 'harmless'

The hazing ranges from subtle to violent. Subtle hazing is erroneously accepted as "harmless." It includes depriving younger members of privileges granted to older ones, name-calling, and requiring older members be called with formal titles such as "Mr." or "Miss."

Harassment hazing can involve verbally abusing others, forcing victims to wear embarrassing clothing, requiring them to perform humiliating stunts, forcing them to simulate sex acts, and making them harass others.

Violent hazing can be deadly. Examples are forcing victims to consume large amounts of water, making them consume alcohol or drugs, beating, branding, and burning them, forcing victims to mistreat animals, coercing them to perform illegal acts, tying them in bondage, and exposing them to extreme cold or heat.

Hazing is bullying. To bully is to frighten, hurt, or threaten a weaker person or to cause someone to do something by making threats or insults or by using force, according to Merriam-Webster.

Mob behavior

Hazing is mob behavior. A mob is a large group that is angry or violent, the dictionary says. Mobs can generate emotional excitement that can lead to atypical behaviors.

The damaging effects of hazing: Victims often don't report incidents because they don't know whom to tell, don't want to "tattle" on peers, or don't think their leaders would understand. They may hide the true cause of their injuries, isolate themselves from friends and family, and stop going to classes. Hazing can destroy self-esteem, self-confidence, group cohesion, and friendships. It can induce or worsen psychological illnesses, such as depression, post-traumatic stress disorder, and anxiety.

The ripple effects of hazing: If it's uncovered, coaches may lose their jobs. Seasons may be canceled. Scholarships can be lost, and schools' reputations tarnished.

Puzzling? Yes. Preventable? Yes. My advice:

Start talking with your preteens and teenagers about hazing, bullying, and mob behavior; they need to recognize them when they occur.

Victims of hazing need to seek a parent or a trusted adult at school even if they voluntarily participated in hazing.

Observers of hazing need to take action, too.