controller.rb

def view
  @ibs = <<-EOF
this is a test
testing

1 2 3
   4 5 6
EOF
#=> "this is a test\ntesting\n\n1 2 3\n    4 5 6"
end

view.html.haml

= form_tag briefing_briefing_sheet do
  = hidden_field_tag :ibs, @ibs
  = submit_tag


-#
  In the above, the :ibs hidden_field_tag represents the value as:
  "this is a test\n  testing\n\n  1 2 3\n      4 5 6"
                   ^^           ^^       ^^  --notice the extra indentation, which
                                             --effectively changes the value of the :ibs hidden_field..