Gag Shock Gum
Good old shock gum, a prank from way back that still works! Looks like a pack of gum (well sorta, we'll explain later) and if you grab a piece, that person gets a slight shock.
You get 1 random pack of gum that's designed to look like a popular brand of gum. It's a really cute and inexpensive novelty item. I remember when I was growing up and I saw these in comic books and novelty shops and even back then I thought it was old. This was around probably in the 1930's or 1940s. But kids today still get a kick out of pranking people, and this might still work.
The shock it delivers isn't huge, but you can definitely feel it! It's probably not best to be used on seniors or people that might be sensitive to shocks. (We can't think of anything this would really do to hurt someone or set them off, but you never know...)
Anyway, that's why the packaging says "Shock Chewing Gum". There are also warnings on the side of the package in fine print. So if anyone examines the pack of "gum" closely they'll see it's not legit. But you can cover up the pack with your hand as you offer them gum. It should look enough like the real thing to pique their interest! :)
This is still a lot of fun after decades. It's a timeless little prank and should elicit some smiles for sure.
Note that you can't change the battery on this, but it lasts for a long time. They're cheap enough at 1.23 (shipped) that you can buy a new one if the battery ever runs out on you.