Wal-Mart (WMT) on Tuesday announced it would release thousands of the hard-to-find Elmo T.M.X. dolls for four days this week via its online site.

"We're very excited to surprise our customers with one last, big opportunity to purchase the hottest toy of the year — Elmo T.M.X. — for only $39.97 online at Walmart.com," said Mike Simas, Walmart.com's vice president of merchandising.

"This really gives our customers more shopping flexibility and the chance to top off their gift lists with the toy everyone is trying to find — at a great value on our site."

Beginning Tuesday, the world’s largest retailer was to release approximately 4,000 Elmo T.M.X. toys every day until Friday on Wal-Mart.com on a "first come, first serve" basis.

The latest incarnation of Elmo laughs when he's "tickled" on his chin, stomach or toe. The lovable fuzzy red Sesame Street character slaps his knees, falls to the ground in bursts of laughter and kicks his feet, making him a popular pick among parents and children this holiday season.

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"He's resonated with both adults and kids," Fisher-Price spokeswoman Brenda Andolina told FOXNews.com last month. "Adults are buying him for the office, goofing around with him, and parents are trying to find him for their kids."

The $40 T.M.X. Elmo was kept totally under wraps in the months leading up to his September release in stores, with Fisher-Price playing up the "top secret" element to generate more buzz.

Apparently, the ploy worked: The new Elmo sold 250,000 units its first day out, and people are on waiting lists to buy him, according to independent toy consultant Chris "The Toy Guy" Byrne, a contributing editor at Toy Wishes magazine.

FOXNews.com's Catherine Donaldson-Evans contributed to this report.