I know this dude who has chicken pox. what is that?

Chickenpox-no fun!: Chicken pox is varicella-zoster virus infection. Before the chicken pox vaccine became available in the US in 1995, almost everyone had this infection at some point in childhood. This virus causes fever and a blistery rash, and can also cause pneumonia and brain infection! That's why the vaccine is so important -- make sure you've had both doses.

A viral infection: Chicken pox also known as varicella, is the primary infection caused by the varicella zoster virus. It causes a widespread rash that can have blisters/pustules and then the lesions scab up. It can be spread by direct contact with the rash as well as the respiratory route. It resolves on its own within a few weeks. Immunizations are available to prevent or minimize varicella infection.