NEW YORK: Bud Light said it with beer cans and Martha Stewart with red velvet cake as companies and celebrities from Beyonce to George Takei joined millions of social media users in posting and tweaking a simple red logo in support of gay marriage.

A square box with thick pink horizontal lines, the mathematical symbol for equal, was offered for sharing this week by the Human Rights Campaign as the US Supreme Court took up arguments in key gay rights cases.

The image is a makeover of the advocacy group's logo, usually a blue background with bright yellow lines. The HRC made it available in red - for the color of love - on Monday and estimated tens of millions of shares by Wednesday.

''It shows the enthusiasm and the passion,'' said Fred Sainz, a spokesman for the nonprofit in Washington, DC. Some swapped matzoh for the pink lines as Passover got under way.

Beyonce, with more than 44 million followers on Facebook, added a personal message: ''It's about TIME!!! (hash)EQUALITY (hash)MarryWhoYouLove."

Fergie let the image speak for itself on Twitter, adding: ''No words necessary.''

Montana Sen. John Tester, a Democrat who endorsed same-sex marriage on Tuesday, put the logo up as his profile on Facebook while the clothing site Bonobos swapped its usual Facebook picture for the red square using fancy white pants for the equal sign.

Martha Stewart's Facebook page used a slice of red cake with white icing to make the image and the HBO page for "True Blood" added fangs.

''There's a lot of serious conversation going on, and there's an awful lot of important concepts that the Supreme Court justices are discussing,'' Sainz said. ''What this logo going viral means is, individuals have reduced it to a very straightforward concept.''

Steve Jones, a professor of online culture and communications at the University of Illinois at Chicago, wondered whether all the mash-ups muddle the message.

"Once you throw it together with something like Grumpy Cat it's fun," he said. "But was this message intended to be fun?"