This is possibly the only union I could get behind:

Complaining of low pay, cold rooms and air laden with paint fumes and charcoal dust, models who pose nude at a Philadelphia art school voted yesterday to join a union.
"We were at a loss about how to get the schools to pay attention to us," said Claire Hankins, 39, who led the effort to organize artists' models at the Moore College of Art and Design.
The union vote came after the National Labor Relations Board rejected the school's argument that the models are independent contractors.
"We feel they are sporadic, occasional employees hired for a specific service, as opposed to employees that we can depend on," said Moore President Happy Craven Fernandez.

Depend on?