If i get the classic "How did you do that?!", i usually work further on it. Truth be told, i havent performed much yet, but it'll come.
One day, i was doing an ACR routine for a friend. It was just a very simple trick, starting with me sliding off the card from the pack and down to the middle of the deck - you know what im talking about

After a "How did you do that?!" i could continue my ACR routine by saying "Look, i take the card, put it in the middle (shows the card) and then i put the other cards on top". Works great with passes
Another classic is the "Can you teach me that trick?! Please?! Can you!", to which i just reply "Yes" and go on to the next trick. It usually takes a few seconds for them to realise that i just answered "Yeah, i CAN teach you that, but im not"
