Sticking needles in subjects is a bad idea

Sometimes you'll see hypnotists who use suggestion to make a part of their subject's body (like their nipple or finger) numb and then do something like stick a needle in it or hold it in a candle flame.

I have to say that while this can be an impressive-looking party trick it is, in general, a bad idea and I strongly recommend that you don't try it with anyone. It's a bad idea for a few reasons:

• Obviously, if you penetrate the skin with a sharp object of any sort, regardless of whether your subject feels it or not, there's a risk of infection. And if there's blood involved then it's not just the subject who risks infection--you do too; you risk catching something from their blood.
• Things like nipples have a very large number of nerve-endings in them; that's one of the reasons that they are so wonderfully sensitive and responsive. Sticking needles into them or heating them up in a flame will damage some of these nerve-endings and sensitivity will be lost for good. It may not be much each time you do it, but it builds up each time you do it.
• Pain is mother nature's way of saying that damage to the body is occurring. If you suppress pain via hypnosis then there's the risk that serious or irreparable damage or injury will occur without your subject even feeling it. Applying the flame of a candle to a finger, hand or nipple briefly... well, anyone can put their hand in a candle flame for a moment or two and only feel a bit of warmth. The problem is that when you hold a candle up to, say, your lovely partner's nipple how do you know when it's too long, when it's starting to burn? Just because they can't feel anything won't stop the flesh charring.
• I don't like hypnosis for parlour tricks. To me hypnosis is a tool to be used to achieve, amongst other things, greater intimacy. And a key to greater intimacy is trust. Using your partner's body and hypnotic responsiveness for cheap and damaging tricks does not seem to be a great way to build trust.

So, all in all, for a quick thrill it's not worth it in my opinion.