I've leveled up sneak to the point that I can roll around like a madman, and I have max pickpocketing as well. What I do is I roll towards a person (usually a guard, because they're freaking EVERYWHERE) and pickpocket mid-roll.

I imagine that in-universe, it's like magic. I roll by people, and their clothes disappear.

It's a strange thing, taking people's clothing without them noticing.

Leave the NPCs boots on and they will walk around with nothing but boots..... For ever...... for ever...... for ever

Im playing a thief this go around and doing PP for the first time. So far 2/5 and the first perk that increases when you PP a sleeping NPC. I think I'm only at 31 or 32. Liking it so far.

so true but this is a magical world so anything's possible.
Can you pickpocket Tullis' or Ulfrics clothes off their back?

Nope. You need to kill Tullius for his armor and the same for Ulfric. You can pickpocket them off of Thames Bryling though. After you've done that wedding part of the Dark Brotherhood.

figured as much. I'm playing my first Imperial who would look good in Tullius armor but he has to side with the rebels to get it. This gives me a RP idea though, I can play him as the betrayed legion general who seeks revenge on Tullius or something

That actually does sound pretty funny! You must be known throughout skyrim as the fearsome 'roley poley' thief

Pickpocket a Briarheart

Pickpocket was painful for me to level, I had to resort to the pickpocketting trainers gold back to level it method.