Fingerlings are officially the biggest toy of this holiday season - and they might already be impossible to get before Christmas

Instagram/Fingerlings

Everyone is talking about Fingerlings - even Ellen DeGeneres.

• Fingerlings are robotic monkey toys.
• They're the must-have toy this holiday season.
• Retailers are having trouble keeping them in stock, both online and in-stores.

Robots are taking over - and they're adorable.

We're calling it: Our prediction that Fingerlings - a robot monkey that makes noise and attaches to fingers - would be the hottest toy this holiday season has come true.

Demand for the toy, which is made by WowWee, has outstripped all but a handful of rivals. The high demand seems to be at the same level as Hatchimals were last year.

Walmart described supplies for the toy as "tight" during a conference call with reporters earlier in November.

"Fingerlings have been hot and remain hot," Walmart US' merchandising head, Steve Bratspies, said.

Facebook/Fingerlings

Fingerlings.

In some stores, customers take the toy off the shelves as soon as it's put out, he said. Retailers only get a limited quantity of the toys at a time. A store manager at a Toys R Us in New Jersey told CNBC that the Fingerlings sell out within hours of being put out on the sales floor.

On Walmart.com, all four colors of the toy are out of first-party stock. Target's version comes with its own exclusive play set and is also out of stock online. Fingerlings are also completely out of stock on Amazon, where they are sold only by third parties at a 100% markup or more. Toys R Us, which sells an exclusive unicorn version, is also out of stock online.

Retailers will be getting stock of the toy throughout the season, but the demand has far outstripped supply. That's causing frustrated would-be buyers to turn to marketplaces like Ebay, where the toy sells for multiples higher than its $15 list price.

That's not turning many buyers away, as Ebay says a Fingerling toy was sold every 35 seconds on the site from November 1 through November 16.

Counterfeiters have also caught onto the craze, and manufacturer WowWee has started fighting back. In October, it sued 165 makers of fake Fingerlings. Earlier this month, it obtained court approval to freeze the assets of the sellers of counterfeit toys.