Kylie Jenner boob job rumors are going viral again after fans compared her before and after photos. But Kylie dismissed the plastic surgery speculation in a series of tweets.

Kylie shocked fans this week when she had added curves up top in Snapchat and Instagram. That had some wondering if she had gone under the knife to get implants. But Kylie took to Twitter and denied getting plastic surgery. When one fan asked her when she got a boob job, Kylie replied, "Um never."

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From there, Kylie continued to answer questions about her before and after photos. And she insisted there was a simple explanation for her newfound curves. When another fan asked for Kylie's secret to big boobs, she wrote back, "It's that time of the month lol." She later told another fan, "They will deflate soon. And it will be a sad sad day."

Kylie Jenner Before Photo Kylie Jenner's breasts were noticeably smaller at the 'Hunger Games: Catching Fire' premiere in November 2013 (Photo: Splash News).

Another fan then wondered if Kylie Jenner got a boob job during her brief absence from Snapchat. But she asked that fan, "Do u want to feel them to validate?" (Kylie later confirmed she wasn't mad at the fan, just flirting). Kylie's Snapchat absence was more likely the result of her bout with food poisoning.

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Of course, Kylie Jenner has faced boob job rumors in the past, as well. In the past she has said that push-up bras made her look curvier. Yet she confirmed on Thursday that she wasn't wearing one in her latest photos.

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"I don’t share this with a lot of people, but everyone thinks I’ve gotten breast augmentation recently, but I haven’t," Kylie wrote on her website in September. "I just use the Bombshell by Victoria’s Secret. It’s life-changing. I’ve gotten all my sisters on it and all my friends."

Kylie Jenner Before After Photos Kylie Jenner showed off her larger boobs in a series of Instagram photos this week.

She added: "Clearly, it's like, 10 times bigger. No contouring, no nothing. This is, like, all padding here. I think it makes your breasts look great, and girly. This is it. No breast implants, no surgery ... it's amazing."

Kylie also had to deny boob job rumors last summer. In June 2015, she said on Snapchat, "To whoever thinks I had breast implants, there’s a whole lot of tape in there holding these up."

Were you shocked by Kylie Jenner's before and after photos? Let us know your take in the comments section below!