gistfile1.rb

xxx = Symbol.method_defined?(:call) && Symbol.instance_method(:call)
Symbol.class_eval { undef :call } if xxx

# some code that fails when call is defined on Symbol

Symbol.instance_eval { define_method(:call, xxx) } if xxx

def stfu_slop
  call_method = nil

  if Symbol.method_defined?(:call)
    call_method = Symbol.instance_method(:call)
    Symbol.class_eval { undef :call }
  end

  yield
ensure
  Symbol.instance_eval { define_method(:call, call_method) } if call_method
end