How can you tell if someone is faking that they passed out to get out of a jam?

Test: If some pretend to be unconscious , a simple test may give a hint of malingering, laying this person on his/her back and raising this person arm at the level of his/her face and let it fall, if the person is really unconscious his/her will fall and hit his/her face but if she/his faking it , he/she will direct his/her arm away from his/her and let fall to the side.