As per Brian's suggestion, I used his workaround this way:
(IMHO, JSON ought to handle this automagically.)

require 'json'
def json_parse_kludge(data)
  return JSON.parse('[' + data + ']')[0] if data.is_a?(String) &&
data[0,1] == '"'
  JSON.parse(data)
end

Fixes my issue:  json_parse_kludge(JSON.generate('\\'))

irb(main):001:0> require 'json'
=> true
irb(main):002:0> def json_parse_kludge(data)
irb(main):003:1>   return JSON.parse('[' + data + ']')[0] if
data.is_a?(String) && data[0,1] == '"'
irb(main):004:1>   JSON.parse(data)
irb(main):005:1> end
=> nil
irb(main):006:0> json_parse_kludge(JSON.generate('//'))
=> "//"
irb(main):007:0>

Thanks again, Brian!

Aaron out.