Teen Mom OG star Catelynn Lowell was not happy with Mackenzie McKee joining the show at the last moment, and McKee quickly responded to the shade.
"If it's not broke don't fix it!" Lowell wrote, adding the hashtags "Teen Mom OG" and "Just Saying."
"Wow I thought better of you Cate. I didn't realize you're such a mean girl. Yikes," one fan wrote back.
McKee saw that, even though Lowell did not mention her in the initial tweet. She responded to the fan, quickly writing, "Same."
Another fan defended Lowell, asking the other fan why Lowell's comment made her a "mean girl."
"She's not being welcoming to Mackenzie joining the cast. It's rude. A lot of these girls on the Teen Mom franchise act entitled," the fan fired back.
On Monday, just a week before the new season of Teen Mom OG debuts, sources told Radar Online that McKee will "appear in a few episodes towards the end of the season." Another source described it as a "trial run" to determine if she could be promoted to a full-time cast member for the following season.
McKee will replace Bristol Palin, who left the series after only one season. Palin, the daughter of Sarah Palin, was brought on last season, along with Are You The One?'s Cheyenne Floyd, to replace Farrah Abraham.
The third time was the charm for McKee. She first appeared on 16 and Pregnant in 2012 before she appeared in the short-lived Teen Mom 3 in 2013. She was in the running to join Teen Mom 2 at one point, but lost out to Briana DeJesus. She was also reportedly being considered to join Teen Mom OG before Palin and Floyd were hired.
McKee's story could focus on her mother's cancer battle. She also made headlines in May when she lost her dog because her neighbors accused her of abandoning her dog. McKee said they left their dog in an outdoor pen while she was on a cruise in the Bahamas.
"So we left our dog in an outdoor pen. Not a kennel, a pen," McKee wrote in a now-deleted Facebook post. "We've had someone feeding and watering him daily. Our neighbors called animal control saying they haven't seen anyone ins days, and they went and grabbed him out of our back yard and just called letting us know we owe them $80."
McKee continued, "Is this even allowed? I'm about tired of how they have done us... They have us on [Facebook] and can easily message us."
Teen Mom OG's new season kicks off on Monday, June 10 at 9 p.m. ET on MTV.
Photo credit: MTV