I'd probably use black hoodies, get a large soap bar stencil for the back and use a bleach spray. 
Discussion
Stencil and bleach spray would look mad.
The bleach stain would almost be the right shade of orange.
I'd probably use black hoodies, get a large soap bar stencil for the back and use a bleach spray. 
Stencil and bleach spray would look mad.
The bleach stain would almost be the right shade of orange.