During last year’s holiday season, people started popping into a baking forum on Reddit with two million members to share a photo and ask a burning question: What on earth is this cookie cutter supposed to be?

The earnest answers often helped clear up the bakers’ confusion. Quickly, however, the posts began surfacing so often that one member created a subreddit dedicated to untangling such cookie-cutter mysteries.

The forum on Reddit is called r/WhatIsMyCookieCutter, and its popularity — membership surged this fall to more than 250,000 people — says something about baking. Without packaging or instructions, the shape of a cookie cutter picked up at a secondhand store or rescued from the recesses of a silverware drawer can be hard to interpret. Is it meant to be a reindeer? A dinosaur? The state of Wyoming?

On r/WhatIsMyCookieCutter, there are no wrong answers. As more members arrived, the group evolved into a self-contained world of inside jokes and running gags. Others respond to queries by uploading renderings of what a cookie cutter might be, often using a drawing and painting app like Procreate to sketch out their whimsical and colorful suggestions.

Over time, these drawings became as much the focus of the subreddit as answering questions about the shapes. One person finds a rose in every cookie cutter. Another sees nothing but pineapples. Recently, the bill from the “I’m Just a Bill’ segment on “Schoolhouse Rock!” has made cameo appearances.

“In the early days, there was a very specific purpose for this sub, which was to identify the shapes of the more unique cookie cutters out there,” said Tes Reilly of Washington, D.C., an avid cookie decorator and one of seven current moderators of the subreddit. “It was practical.”

Now, “people are not here because they are avid users of cookie cutters with pressing questions,” Ms. Reilly, a doctoral candidate in media psychology, added, “but because the drawings are hilarious, the inside jokes are comforting, the attitude is always positive and despite its size or form, it is a very real, very meaningful community.”

One spent so much time finding a way to draw the state of Wyoming into virtually every shape posted that she felt obligated to issue a formal farewell last month when the subreddit became too much of a distraction. “I’m saddened to announce that I won’t be doing any more Wyoming posts,” she wrote. “But I’ll definitely still visit.” The post received thousands of upvotes and hundreds of comments.

Another drew a rose in so many cookie cutter shapes that the image became something of a symbol for the community, inspiring bakers to recreate it in their icing designs. “In honor of our special friend,” one post reads, accompanied by nine cookies, all decorated with icing to look like the flower.

“Reddit and Reddit users in general get a bad rep on other social media platforms, but this subreddit proves just how wholesome users can be,” said Angelina Cannon, who lives in Middlesex County, N.J. Ms. Cannon said that she did not have much baking experience, but that she was drawn to the subreddit after following similar identification forums, such as r/WhatIsThisThing.

“I really wasn’t expecting all the art when I joined, but it definitely kept me interested,” she said.

There are a few rules, No. 1 being that every post must be cookie-cutter related; another prohibits the sale of cookie cutters. The moderators try not to stifle creativity or fun, aiming to maintain a spirited atmosphere.

“I’ve been part of some communities where the moderators are too hard or strict,” said Garyn Greene of Ohio, who recently joined the group’s moderation team after noticing the subreddit’s rising popularity. “I like making sure it’s whatever the community wants it to be.”

Even with the self-referential jokes, open-ended rules and growing sense of camaraderie, the subreddit still serves its original purpose. Last month, for example, a baker posted a photo of the only cookie cutter they had yet to identify from a set. People populated the comments with drawings of a giraffe, a “check engine” light and, of course, a pineapple. A sewing machine, many were surprised to learn, was the right answer.

Not everyone appreciates the turn the group has taken, but there have been few negative comments, according to the moderators. To keep people engaged, there are plans for contests and online events.

Whether you see roses in a Christmas tree or Wyoming in a circle, Ms. Reilly said, there is one thing that everyone can agree on this holiday season: “I mean, who doesn’t love cookies?”