Jenelle Evans wants fans to know that her boyfriend's mysterious skin mark is most definitely not AIDS -- just in case anyone was not clear.

According to a new report, the Teen Mom 2 star and mother of three went off on a fan on Instagram after the fan made shocking allegations against the man she will soon marry.

"It's called vitiligo you f**king idiot. It's a loss of pigment in your skin," Evans explained of a mark seen on Eason's hand, as reported by In Touch Weekly on Monday. "People are models these days for it. You need to research STDs if you don't know wtf AIDS does to you.... and def don't do that s**t to your skin like that. Maybe you're the one with AIDS and don't even know cuz your [sic] as dumb as a box of rocks my friend."

Evans and Eason began dating in 2015 and will tie the knot later this year.

Along with Evans' two children from previous relationships, Jace and Kaiser, and Eason's two children from previous relationships, the couple also shares a five-month-old daughter, Ensley Jolie.

Months ago, Evans spoke to E! News about her hectic life at home.

"Life is pretty complicated at the moment, but I love it and wouldn't trade my role as 'mom,'" she explained.

As for more kids in the future, Evans claims she and Eason are done.

"David and I talked about it one day recently and how complicated things can get with Kaiser and Ensley together. They remind us why we are done," she said.

To see more of Jenelle Evans and her family, including her fiance David Eason, tune into the upcoming eighth season of Teen Mom 2, which premieres on July 17 at 9 p.m. on MTV.