During last night's Grammy Awards, the Red Hot Chili Peppers joined Post Malone for a performance. Of all the live collaborations that took place during the ceremony, theirs was the one that raised the most eyebrows. Post kicked off his time onstage with an acoustic version of his song "Stay," but as soon as RHCP took to the stage alongside him, things got a bit messy.

Needless to say, people on social media were quick to criticize the performance. With its muddy sound mix and clash of vocal styles, it didn't turn out quite as well as fans of both acts were hoping.

Post Malone also attracted attention on Twitter for the 21 Savage t-shirt he wore to the event, which was hard to spot during the performance due to his jacket. Fans were expecting Post to give his friend and "Rockstar" collaborator a shout-out, but he didn't do anything beyond wearing the shirt.

Some people were critical of what they perceived as a lack of support for 21 Savage from Post, who responded to the criticism directly. "1st thing you see when you look at my shit is support for my FRIEND," he tweeted. "Y'all can say what y'all want about my career, but not this situation." One of 21 Savage's managers responded to the situation, too, stating, "It's all good bro."

Check out some of the most notable reactions to the performance below.