I've been trying to come up with a meaningful, sincere way of answering that question without having to resort to cliched one liners and without breaking the illusion/magic.
I really love this response as well. I think it's the best way to do it if you don't have that mystique vibe to you that makes you seem like you actually posses dark magic powers hahaFirst off, there are two different ways the expression "how did you do that" is used. The first is an expression of disbelief, translated as I can't believe what I just saw. No response is needed. The second is a genuine question where they want to know the method for what you did. Either way, I usually respond by going over what happened in the effect.
"Well, you picked a card, showed it to everyone, put it back in the deck and then I waived my hand over the deck... it actually gets a really complicated from there." Then transition into something else. "But that reminds me there is something else I wanted to show you...."
It may not work with everyone's style, but it works for me. It reinforces the idea of what they've seen, it seems like you are going to respond and then you stop because it is too difficult to explain. Then you transition on to something else. I do it in a lighthearted and disarming manner, but it is clear that I'm not going to give away how I did something. I also quickly redirect their attention to something else.
what i usually answer to someone who asks " how did you do that?" is "very well, thank you"
they wont inquire further unless they are truly interested.
As a purely personal note, I hate that response. First off it's very cliche. Second, it's patronizing and arrogant.
As Reality said, there's two ways people generally say this. The first is, "How did you do that!" It's an expression, not a question. You should not respond to this at all, as any response will probably break them out of that moment of wonder and destroy it with your hubris or clumsy attempts at humor. Just be quiet and let them experience it for a bit.
The other way people generally say it is, "How did you do that?" An actual question. I say you should still not respond, as often this is still just a response out of wonder. If you're performing well people might get into this mind set where they are just voicing their thoughts. I don't respond to this unless they ask more than once.
Personally, when I'm really entertained and fooled by something, I usually say, "How did you do that ..." .. I do not want a response. I'm not talking to the performer, I'm talking to myself. If you try to be witty, you'll distract me and I'll stop being entertained by you, I'll be irritated and wish you'd just shut up.