A person once told me they were not impressed with a magician's trick because they knew there was no way he could really be making an item disappear or whatever the scenario was. I thought that was a rather distorted view of magic.

I did some tricks for a few kids and one of them thought I had a magic ring that had powers in it so I took it off and they said no the ring gives you power until you destroy it and they expected me to destroy my ring. And when I didn't they said see I knew it its a magic ring.

Was doing a birthday show and the birthday boy said I was a demon...

I did a couple g*ff card tricks and this woman was absolutely certain I was using telekinesis to physically pass the cards through each other...

On another occasion, at the first kids birthday party I worked (yeah, I know, working for kids is like herding a pack of wolves while wearing Milk Bone blue jeans) and I went through a typical card routine. I knew a great deal of the card tricks would be right at eye level for a bunch of kids so I chose the tricks I knew were as clean as I was capable of, you'd have to be a sharp cookie to see what was happening. This one kid, I don't know if he wanted to be a magician when he grew up or if he just read a lot of card magic books, but that little scamp never missed anything. Nothing got by him and he told his friend (the birthday boy) every single thing I did to do the trick, sometimes before I'd even do it. "Watch Billy, watch, he's gonna hafta carry that card up, watch, watch."

In comparison, at least with the woman who thought I was moving the cards with the power of my mind, I had it on my side that nobody took her seriously. With Little Mister Card Whiz, it was like performing with somebody on a PA giving play-by-play, lol. It's alright though, what better gift can a little boy get than a guided tour of a dozen different card effects?

How old was he?
Haha I have been called a demon many times especially late night performing to intoxicated individuals, they had the best reactions however.

Chinese linking rings (normal size rings, not close-up)
"You put the unlinked rings up in your right sleeve and get the linked ones in your left sleeve".
This is incredible, because I always use rolled up sleeves.

When producing a silk from a TT a kid was unimpressed and said "you have tubes in your arms"

While waiting for the coffee to pour I showed scarf through neck for a colleague
she grabs my wrist and with wide open eyes and said "did you hypnotize me?!?"

I do a simple drawer-box routine from which I produce Ember, my corn snake. One youngster approached me, convinced that I had that snake up my sleeve the whole time. I can't imagine either of us would be comfortable with that.

One of my favorites was when I totally messed up an OTL effect where the participant drew a picture of her choice (a snowman) and initialed her card. The intent was to make the snowman disappear, but due to poor instruction on my part, the initials disappeared leaving the snowman. She was still astounded, but figured I merely switched cards with one that was pre-drawn wanted to know how I influenced her into drawing a snowman. I smiled, winked, and let her believe I had that sort of ability.

I've also been accused of using heat-sensitive cards and the like, but my favorite (and most satisfyin) is when I've been accused of witchcraft.

Had a dad watching, he went away and used his cell phone, then came back and announced that I just did it by slight of hand. I hope he didn't tell to many other people.

I'm working on a "particle physics" explanation for the cups and balls using the Quark.

It's absolutely absurd, is beyond the grasp of most people who have better things to do than read about them, and would be a stupid explanation to anyone who has done even a cursory study.

I think it'll be funny, but I have a hard time these days remembering the varieties of quark...

Actually it would be funny if you had a patsy in the audience who would constantly be on the phone "researching" what you're doing as you're doing it and "calling you out".
Unfortunately I can't get anyone I know to be the heckler in the story of the day I met El Diablo... and that's only 2 questions, so I couldn't make the idea work.

One ring to rule them all...

David Williamson has a hilarious story about frying a spectator with one of his card routines and her attempts to explain things. It's near end of performance section in his Penguin Lecture. I can't do it justice, but if ever get a chance, watch it.