I loved the book "Tricks With Your Head", Jordan, and it reminded me of one I did back in my mid 20's.
This takes a while to set up, and it only works (generally) in the Deep South, where you may be part of a family in which eaither Grampa or Gramma dips snuff.
It's a little disgusting but here goes:
What they see: You, in the chair vacated by Grampa or Gramma, looking down at the floor beside that chair and exclaiming, "Oh, look! Peaches! I love 'em!" Then you pick up a large can
(ostensibly fit with snuff spit), turn it up and drink it down.
What actually happens: This will take some preparation, but I promise it'll be worth it. Next time you're at the grandparents, notice the brand of peach can (it's usually peaches, but if not, you need to make sure it's a fruit of some kind, or this won't work) but the cans have to match exactly, size and all.
Then next time you're at the supermarket, you buy exactly that can, take it home, dump almost all the peaches into your wife's Tupperware bowl, cut the top off and now you've got your prop. You want to buy that can the day before your visit, so when you drink it down, it won't make you ralf if it went bad.
Cover that can with Saran wrap and put it in a cooler (just small enough to hold the can) with a little bit of ice the morning of the visit, and put it in the trunk of the car - out of the way.
Special Note: Most old folks cover that can with a piece of newspaper, so make sure you have one whole one with you.
Here's where you have to be a little inventive, but I know y'all can do this, because you're Super Magicians......
Okay, now you're in the house, the table's being set by the ladies and the kids, you're probably schmoozing with the other guys, and now you're being called to dinner.
Very tricky, but you have to excuse yourself, go to the car and find a way to get that can (and maybe the newspaper) out of the cooler and hide it where you can get to it easily. It's got to be out of sight, but close by - very important.
Now, you have to be the last one to the table and the first one back to where everyone's going to be sitting. Quickly switch your can with the spittoon one, and put the spittoon one out of sight somewhere.
Sit down in that very chair, and start reading the newspaper, and as you finish each section, lay it down strategically near the peach can so people will think you're done with that section. Then, when everyone's back in the room, pick up all the papers, move them out of the way, (lap is fine), look down at the can and say, "Hey! Peaches! I love 'em!", then pick up that can and drink it down, as all the women scream and/or puke, and the kids say, "Duuuuuude".Awesome!", then show it was just peaches, or pears, or whatever fruit.
My wife didn't speak to me for the better part of a week, but I just don't like seeing an old person spit snuff out of her mouth in front of the family. It's just gross and I was making a point.
Nobody puked when I did this, but a couple of women tried to stop me, then screamed when I drank it down.
Guys, this took me the better part of an hour to write and remember, and I didn't do it exactly as I described. I was trying to set it up for you in case your family situation was different; but if you see an error, feel free to correct me and best of all, critique the gag for me.