Hoverboard" with the possibly-exploding battery. It's basically Tickle-Me Elmo ... but less dangerous?
Anyhow, here's my public service announcement: Let the parents buy (or not buy) the trendy toys for their kids. Whether it's an Xbox, PlayStation, Wii U, iPhone, iPad, Paw Patrol, Disney Infinity, LEGO Dimensions, Skylanders, Power Wheels, or whatever is popular at the moment -- it is better that parents buy it for their kids, or at the very least, kids should ask "Santa" for it directly.
People who give gift to not-their-kids should try to give something relatively timeless and not trendy. Why exactly would I say that? A very long time ago, a friend of a relative gave my brother and I these action figures -- anthropomorphic insect-men with large insect pets. It was as memorable as it was ... strange. Of course, it is the thought that counts, but the memory remains. To this day, I have no idea what or where these insect-men are from, and I don't feel like Googling for information. I am fairly certain that they must have been popular in certain circles ... somewhere.
I suppose if your goal is to create weird memories for kids that are not yours, then by all means, give some weird toy. If you want to ensure that your present will have lots of replay, even though the child will eventually forget the giver of the gift, and perhaps the specific gift itself, then here are some last-minute suggestions:
1. Buy an inexpensive Christmas stocking, a tangerine, and as many $1 Hot Wheels or Matchbox cars you can stuff into the stocking. First place the tangerine into the stocking (it's kind of a gag gift at the end of the stuffed stocking). Then stuff the stocking with toys. I have a hypothesis that Hot Wheels aren't meant only for boys, but for both boys and girls. To be sure, try to buy cars that are painted in a kid's favorite color(s). The more cars, the merrier -- there is a lot of replay value in these $1 vehicles.
LEGO Star Wars or whatever, to be sort of trendy, but infinitely reusable as whatever they wish. Be sure there are a lot of minifigures with the bricks; you'll never know if a kid will latch on to a certain combination of minifigure parts and make it his/her sigfig. LEGO can and should be gender-neutral -- but they sell LEGO Friends and pink/purple-themed sets, just in case. While usually pricier than Hot Wheels, LEGO probably has more replay value than any other toy, at any age.
3. A board game. Then again, maybe not. Don't get them a trendy game like the pie-in-the-face one. A kid's parents should be responsible for something like that, if they kid really wants that sort of game. If a household doesn't have basic games like Monopoly, Scrabble, or even a deck of cards (or the app versions thereof), then it'll probably be a cool gift to give.
4. A plush toy or stuffed animal. Depending on the age of the recipient, you can't go wrong with a generic-looking teddy bear. Mickey Mouse and Minnie Mouse are easy choices. You can get a little hipstery and go for Oswald the Lucky Rabbit. Just make sure the plushie has an overall friendly face and non-creepy vibe to it; otherwise, that kid might blog about that strange, anthropomorphic, insect plushie that was memorable ... but weird.
5. A ball, any ball. A baseball. A softball. A Wiffle ball? A football -- American and/or soccer. A basketball. A volleyball. Regulation or smaller. Hard or soft -- a plush ball, perhaps? I take back what I've written earlier: A ball might have more replay value than any LEGO set. In any case, my dog Kate has a Saturn-shaped ball waiting for her after Saturnalia, on Christmas Day.
I'm either too old for a Christmas present, or I'm an overgrown kid with an Amazon wishlist (I can't say for certain which) ... but I'd be excited to receive a die-cast car, plastic bricks, a deck of cards, a plush friend, and/or a ball for Christmas.