I do it on their fingertips

I think the poster is implying "impromptu" - probably from the use of the word "impromptu." Just a guess. I don't think that the question was, "what is the one magic gimmick that you always carry with you?"

Okay, all sarcasm aside, if you can borrow a shoelace and a ring then ring and string magic is quite awesome.

Recap is pretty good - although I have trouble landing that strike vanish 100% of the time with a borrowed pen.

I normally wouldn't say anything with a deck of borrowed cards because most decks I've borrowed are so dirty and bend up that they are useless for most card effects requiring skill. Although, I have a coin matrix that I do that uses a dish towel, 4 quarters and any four card-like pieces of paper - such as crappy old cards or index cards.

Ring and string and Recap.
Greg Wilson fan much?


Lol. Those are actually my two choices too, but I would use my own shoelace because it's kind of a pain for the spectator to put it back.

I'm more of a mentalist so i'd probaly have to say muscle reading

Definitely Thought Chunnel, from Quinn's ParaLies.

Brilliance bottled, more or less. It destroys people..

I like to do some gag body magic, because i can usualy get a laugh from "look! my thumb comes off! its real magic!" and occasionaly you get the person who wasnt really paying attention and is momentarily amazed at your ability to remove your thumb lol. and can somebody throw out a link to that re cap trick? im interested in it, i just cant find it anywhere...

http://www.penguinmagic.com/p/466

There you go.