CBS Los Angeles reports on the latest AHF billboard controvery.

The latest billboard campaign by AIDS Healthcare Foundation (AHF) in Los Angeles suggests that people who use mobile dating apps should get tested for sexually transmitted diseases at FreeSTDCheck.org, which is a resource run by the foundation.

However, not everyone is on board with the hookup culture awareness campaign. Tinder, an app that is named in the billboard, sent a cease and desist letter to AHF, the Los Angeles Times reports.

AHF responded that it will not remove the billboard.

The billboard shows silhouettes of four people’s heads. Over each is one of these words: “Tinder, Chlamydia, Grindr, Gonorrhea.”

“In many ways, location-based mobile dating apps are becoming a digital bathhouse for millennials wherein the next sexual encounter can literally just be a few feet away—as well as the next STD,” said AHF’s Whitney Engeran-Cordova in a prepared statement.

Tinder attorney Jonathan Reichman responded in a letter: “These unprovoked and wholly unsubstantiated accusations are made to irreparably damage Tinder’s reputation in an attempt to encourage others to take an HIV test by [AHF].”

This isn’t the first controversial billboard campaign by the AHF team. Earlier this year, the organization drew fire for its “Trust Him? / Trust Her?” ads.

AHF has also waged a battle against Truvada as pre-exposure prophylaxis (PrEP), though recently AHF appears to be ceding ground in its anti-PrEP fight.