Some finger magic is great for a casual setting. I'm partial to Pinky thing by Nick Locapo and Breaking point by Johannes Mengel.

For me this effect below is never fail to amaze them:
Glass thru table
Free Will prediction
Spoon bending
Phoa Yan Tiong cut restored napkin
Spellbound coin change
Cigarette ash thru palm

As I've said in similar threads, I'm really never without anything as I always have at a minimum my Stealth Assassin, with blank slips, and a pen. That said, if I had the misfortune of losing it or having it stolen, a go to impromptu effect would be a utilization of Phil Smith's Quinta which works very well for me.

Carter

I've been wanting to say this for a long time:
SLIGHT OF HAND

Here are some things I discovered.
Why should you do magic when someone asks you. Yes, I think that cheapens it all. But, I really want to do magic.

I had this trouble when starting to do some standup gigs. I ran into many people asking for a free show as the event was for some charity deal.

A pro offered this. Say you will do the show for no charge but you need something in return. For some group asking for a freebee, they can put a picture in their club paper or even in the newspaper. That is, you get free advertisement for a free show. The idea here is when someone wants to see magic, see if you can get something from them. It is interesting what they come up with.

As for an impromptu trick. Here is something I discovered. It is called the center tear. Yea, I know its old but it can kill. I was in a restaurant and wanted to do something. I tore a corner off the paper placement. I drew a circle on it and asked the person to draw something in the circle. They did and then I asked them to fold the paper in half and in half again. Then I took the paper and tore it twice. Then I dropped the pieces into a glass of water. In doing so, I copped the center. Then I stirred the water and took a sip. During that I got the information. Then I went through the mentalist shtick revealing what they put on the paper. During a bit of cleanup, I dropped the center into the glass. It killed.

Well, perhaps this is not the greatest but I'll bet the day will come when you will remember this at one of those awkward moments.

Tanks, Al. There is a wise suggestion from you I use when I can. I got it from your old website. You said it was better to find a place to perform that was separate from the main space of activity when in a house party. Even the kitchen would do. That idea has worked great for me (whenever possible). Small groups come in, and they go out talking to each other, expressing wonder involuntarily. That brings more people in. This could be used to good advantage when one does not carry special items. The Balducci levitation can be done that way for a few people at a time. Darwin Ortiz relates that David Roth used to perform it like that.

A copy of Easy Hand Tricks by Bob Longe is a good thing to have in your library.

Also, if someone walks away without the name of their selected card, or thought-of number, or something on the back of your business card ... consider it.

I realize you said no props, but don't you have your wallet with you always? Perhaps a minor who doesn't drive might not, but I suspect that at some point, everyone will carry a wallet with their drivers license. If so, then you could get a wallet with a zipper compartment and/or a coin pouch and always have rubber bands, coins, gimmicked bills, etc.

However, in the spirit of the thread, let's say you are at a nudist camp with no wallet or anything. I would go with two in the hand and one in the pocket... er, um, one in the... well, wherever you might put it.

KJ

An equivoque routine.

PATEO Force with borrowed objects.

Personally do the one coin routine when I have absolutely nothing with me.

Can also use spectator’s phone ans do toxic force on their calculator.

Train tracking by atlas brookings. the most close thing for a real mind reading

If I'm going to be strict on your question and take it to mean not even coins or a ring, literally no objects on you that you could use, I'd do the finger thru ear, arm twist, or something to that effect.

Glenn

Stigmata by Wayne Houchin and Control 2.0 by Wayne Houchin. Old effects but they are good.

A fun one to do is a matrix routine taught by Darryl on his Fooler Dooler DVD set that’s called “Mystery of the traveling marbles” by Silent Mora. Instead of 4 marbles you can use any small items. I am sure there are many matrixes that have been taught, but this has served me well over the years. Darryl certainly left us too soon

Inject 2.0 - Insane amount of stuff you can do anytime anywhere
Ring Thing - have killed with this for years - hits hard
Magicians Choice - Lay out 5 objects in front of a spec and predict which one they choose. I do not know who originally came up with this masterpiece - but it kicks butt and I would like to thank whoever came up with it.

I perform either the Social Prediction or a Coin Body Loading routine

I never need to carry any magic items with me ...

which hand? - object hidden in either hand
rock-paper-scissors - 100% correct every time
human calendar - any day called for
inject 2 - using spectators phone

I tried a new spin on my favorite impromptu effect. When asked (or expect to be asked) to perform some magic,
I get a pile of small objects. Could be various coins, candies, nuts - whatever.

A spectator selects the two identical objects with which I must perform.
One is taken by my left fingers, the other by my right. (no transfers) Both are visibly displayed on my open palms. Fists are made.
I ask another person which object (named) they believe to be the more powerful. That hand is opened to reveal the object has vanished while the other hand still holds its single object.

What is new is my saying, "Now that you have vanished that object (name), please show us some more magic with it."

or, "Great! OK - where did you hide it?"

I usually will do some stuff with a coin such as Jay Sankey's Messiah vanish and Joe Rindfleisch's Wave Vanish.