The actress, by the way, says there's nothing romantic going on between them.
"Machine gun Kelly Really? I'm out!!! You are now infected," one person commented on an Instagram post of Kate pouring "cat wine" for her feline.
"Why don't you worry about things that are actually happening and donate to the Australian wild fires rather than waste your time on things that are not happening and never were," Kate clapped back, adding in flowery terms that the commenter needs to "get a f—ing life."
Another person told Kate that her post was "tone deaf."
"I don't agree. Donate. You don't need a medal for it," she said.
Kate is known for her epic social media clapbacks, often putting Internet trolls in their place.
"U need a man," another person commented on her Tuesday post. Kate replied, "Maybe you do since it's so much on your mind xx."
Coincidentally, Kate was linked to Machine Gun Kelly's best friend Pete Davidson last year. She also reportedly got "cozy" with Jamie Foxx last year after they were photographed together, but she denied there was a romance.
"I would like to point out that standing next to someone does not mean I am dating them," she wrote on Instagram. "Currently in line at the dry cleaners and if that's true I've got a hell of a problem."