A Tumblr blog gets thousands of followers by juxtaposing classic “Peanuts” cartoons with unrelated tweets. But “Peanutweeter” was shut down in June, several months after launching, due to a takedown notice from Iconix Brand Group, which jointly holds the copyright with the heirs of creator Charles Schulz.

Meanwhile, kiddie show “My Little Pony: Friendship Is Magic” has somehow attracted an adult-male cult following, called “bronies” (bro + ponies), who take footage from the show and combine it with everything from foul-mouthed Wu-Tang Clan songs to R-rated movies like “Inglourious Basterds” (a practice known as “trackjacking”). Copyright holder Hasbro Studios has not only allowed most of the content to remain online, but it released a promotional video paying tribute to its unlikely fans.

Welcome to the confusing world of online parodies, where intellectual property gets manipulated in the name of comedy. And that is forcing content companies to make tough calls as to whether to embrace it all as free marketing or crack down, claiming copyright infringement.

Some, like Hasbro, recognize that the Internet has enabled the tools and distribution to “remix” the shows and movies they love or hate. What was always a passive experience for fans has given way to a participatory culture.

And yet there is still a conservatism that leaves many within the media business wary of those whose parodies could easily be confused with or tarnish their own output. Even worse: the prospect that they could even profit from their appropriation. Lucas Films is often held up as the Darth Vader of content restrictions for repeated clashes with rabid fans of its “Star Wars” franchise.

“You have a lot of people in marketing who think that’s not how the branding should be portrayed, so they should be quashing it,” says Ben Huh, CEO of Cheezburger Networks, a suite of comedy websites that houses many user-generated parodies.

What makes this tricky territory to navigate is the murky legal notion of “fair use,” under which parody is considered one of the key exceptions to copyright restrictions. As a legal concept, parody is like pornography — not easily defined — which explains why many of those who put parody to work have little understanding of its boundaries.

That’s where the platforms that exhibit and/or promote some of this controversial content come in. YouTube, Twitter and Tumblr have all tried to strike a balance between preserving the free expression of their user base while staying sensitive to the content companies that are sources of revenue from advertising and licensing.

YouTube in particular has tried to enlighten its users to the nuances of fair use. The Google-owned site introduced a tutorial on the subject in April, as well as a “copyright school” — a video series that educates users who have been flagged for copyright violations, followed by a quiz they’re required to pass in order to be reinstated.

Regardless of the effort, media companies will likely issue takedown notices to any content they find offensive, and offenders will be intimidated enough to comply rather than question.

Jonathan McIntosh, a self-proclaimed “pop culture hacker” who operates out of website Rebellious Pixels, braces for backlash every time he releases a clever mash-up like his most recent work, “Right Wing Radio Duck,” which mixed footage of Donald Duck with audio from Glenn Beck.

“It makes me happy that it’s going viral (but) at the same time I have this feeling of apprehension that the wrong person is going to see it and try to censor it,” he says, adding that while Beck bashed him on the air, he did not order any takedown.

But even qualified tolerance may seem short-sighted when there’s an opportunity to actively encourage and participate in a parody. Consider what Bear Grylls, star of “Man vs. Wild,” did in May in response to months of fans creating comic illustrations that mocked the wilderness expert’s propensity to drink his own urine when deprived by the elements of more suitable liquids. Grylls tweeted a picture of himself sipping a cup of tea with the message, “Am on vacation in LA. Looks like I’ll have to drink my own pee!”

“Really it all comes down to a question of control for big media companies,” McIntosh says. “They can either attempt to clamp down on remixers and fan communities or they can embrace the new creative digital world and see transformative works as a positive thing for their franchises.”