And just to mention it, as nearly all answers here answer to the question "How can I avoid explicit torture scenes as a DM?"

So after going through the metagame topic of "Is it OK?" (preferrably in advance), and if it is OK, you can role-play it in a nasty simulationist fashion.

Prepare for the session as usual: 

* [research the topic](http://skeptics.stackexchange.com/questions/4498/does-torture-work-well-as-an-interrogation-technique)   
* print out some torture devices (in black and white) and maybe some mutilated human bodies
* play out the two concurrent processes of torture - the dialogue with the NPC, and enduring the actions of the NPC (torturer)
* don't start out by "I'll ask nicely", start with some pain in order to put the subject in a stressed state, where lying would be detectable
* tortured subjects usually get executed afterwords, if they hold no more information of interrest

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> but on the other hand, it's hard to force a player to give up info if he doesn't want to.

    - Just hold still while I am doing to you eye what just happened to your finger.