my belief is that you simply can't ...
you can tell when he's lying with body language.
Answers.com says to Try a truth serum:
(based on: truth drug?cat=health" class='external' title="http://www.answers.com/topic/truth drug?cat=health )
Drugs used as truth serums. Two of the most commonly used truth serums are members of the barbiturate" class='external' title="http://www.answers.com/topic/barbiturate drug class. Barbiturates are sedatives and hypnotics that are created from barbituric acid. They are divided into classes according to the duration of sedation" class='external' title="http://www.answers.com/topic/sedation: ultrashort, short, intermediate, and long. Ultrashort-acting barbiturates are used as anesthetics whereas long-acting ones are used to treat convulsions (anticonvulsant)" class='external' title="http://www.answers.com/topic/anticonvulsant). Barbiturates are controlled substances due to their high potential for abuse and for addictive behavior.
Sodium pentothal (pentothal sodium, thiopental, thiopentone) is an ultrashort-acting barbiturate, meaning that sedation only lasts for a few minutes. Sodium pentothal slows down the heart rate, lowers blood pressure, and slows down (depresses) the brain and spinal cord (central nervous system) activity. Sedation occurs in less than one minute after injection. It is used as a general anaesthetic" class='external' title="http://www.answers.com/topic/general anaesthetic for procedures of short duration, for induction of anesthesia" class='external' title="http://www.answers.com/topic/anesthesia given before other anesthetic drugs, as a supplement to regional anesthesia (such as a spinal block), as an anticonvulsive, and for narcoanalysis.
Sodium amytal (amobarbital" class='external' title="http://www.answers.com/topic/amobarbital, amylobarbitone, Amytal) is an intermediate-acting barbiturate. Sedation occurs in one hour or longer and lasts for 10 to 12 hours. Sodium amytal depresses the central nervous system. It is used as a sedative, hypnotic, and anticonvulsive and for narcoanalysis. When sodium amytal is used for narcoanalysis it may be called an "Amytal interview."
Scopolamine (hyoscine) is an anticholinergic" class='external' title="http://www.answers.com/topic/anticholinergic alkaloid drug that is obtained from certain plants. Anticholinergic drugs block the impulses that pass through certain nerves. Scopolamine affects the autonomic nervous system and is used as a sedative, to prevent motion sickness, to treat eye lens muscle paralysis" class='external' title="http://www.answers.com/topic/paralysis (cycloplegic), and to dilate" class='external' title="http://www.answers.com/topic/dilate the pupil (mydriatic)" class='external' title="http://www.answers.com/topic/mydriatic).
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The main trait of a narcissist is that they see and perceive things only as they pertain to themselves. So if a commonly held truth doesn't correspond to the view of the narcissist, the narcissist will need to create a version of the truth which does.
Yes -- the Narcissist will tell HIS/HER OWN VERSION of the truth and try to tell it first & loudest. Don't believe it.
Be careful if you do, the narcissist can be a monster to anyone who hurts their pride.
If they know that you have figured them out, they will not want to be around you for fear that you will tell people the truth. What they really need is help for their problem.
It's not best to tell him after a while so be straight and tell him
Yes. Otherwise they'll get deeper and deeper into it. At lease they have a fighting chance if you tell them.
You will tell me the whole truth.
If he or she dates people of the same sex.
Tell him, tell the truth dont get your friend to tell him you tell him tell the truth
Yes, but only if he got something out of it.
To Tell the Truth was created in 1980.
They are trying to make you feel bad. Don't buy it. Cut all ties and keep them cut.