Jenelle's boyfriend Nathan and her mother Barbara haven't always seen eye-to-eye, but their past disagreements pale in comparison to the heated -- and unprecedented -- argument in the "Teen Mom 2" sneak peek below.
After Jenelle tells her beau that she and her mom have completed the gift registry list for their upcoming baby shower, Nathan asks if a certain type of high-end car seat made the cut. But Barbara doesn't think the couple needs such an expensive item -- and isn't afraid to voice her opinion about it.
"You better start growing up and realizing that money's not gonna last forever," Barbara says, and her comment doesn't sit well with Nathan.
"Hey, I have a mother, thank you," he spits. "We're two adults, who take care of our own s**t. Right? Your daughter is an adult. I'm an adult. So you don't tell another adult how they should do things. It's wrong and it's disrespectful."
Although Jenelle tries to encourage the two to "be quiet," and Jace even imitates his mother, Nathan and Barbara continue to argue.
"I'm telling you, if you're with my daughter, you will hear from me -- if you treat her wrong," she yells.
That's only the beginning of their exchange of words and accusations. Watch the entire confrontation in the clip below, and be sure to catch a new episode of "Teen Mom 2" on Wednesday at 10/9c to see if Barbara and Nathan can resolve their differences.