Involuntary extension of the "normal" leg occurs when flexing the contralateral leg against resistance. To perform the test, the examiner should hold one hand under the heel of the "normal" limb and ask the patient to flex the contralateral hip against resistance (while the patient is supine), asking the patient to keep the weak leg straight while raising it.
Hoover's sign 
Lockwood's sign
Bing's sign
Fothergill's sign
Adson's sign
Pratt's sign
Dance's sign
Battle's sign