Michelle Kirk was shamed by a man during her run for having "saggy boobs".

Imagine you’re out for a run. You’re sweating, your legs are aching, hair flying all over the place and you’ve got your 18-month-old daughter in a pram with you. An upcoming marathon you’ve been training seriously hard for is the motivation that keeps you going, pace by pace.

All of a sudden you’re stopped by a stranger, a man you’ve never seen before. He doesn’t say hello, cheer you on or even ask for the time – instead he comments on your choice of sports bra that appears, to him, to be making your boobs “sag”.

Unthinkable, right? Not for Michelle Kirk, who this happened to the other day.

Outraged, the 30-year-old from Long Island vented and responded to the rude stranger in a Facebook post that’s been shared hundreds of times.

It’s one big (and literal) ‘up yours’.

“To the nasty old man who stopped me mid run to inform me that I need to get a better sports bra because my boobs are sagging and will only sag more if I continue to run…f**k you,” she captioned the post-running photo with her middle finger raised.

“You are the reason why women have insecurities. If you don’t like the way my boobs ‘sag’ when I run, then don’t look! I will NEVER stop doing what I love and I love myself way to much to have your hate bring me down!”

Kirk was doing the same run she does four times a week around her local neighbourhood, in preparation for the upcoming New York City Marathon.

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The stranger claimed he was commenting out of concern for Kirk’s health.

“He was like ‘your boobs are sagging,’ and then he tried to explain the health aspect of it. He was like, ‘They’re already heading south. I don’t think you want that’,” she told the Miami Herald.

Kirk, not wanting to get too angry in front of her daughter, told the man her ‘non-sagging’ bras were all in the wash so she’d opted for this bra rather than not wearing one at all.

Once home, she wrote the post that’s been liked almost 700 times, posting it on her personal page as well as in a running group.

Image: Facebook: Michelle Kirk

“I can’t stand other people trying to bring other people down. I had to speak my mind. I had to tell someone, and I told Facebook," she said.

While she's amazed at the response from people to her post, there's one person in particular she hopes sees it.

"I don’t want him [the stranger] going around ruining people’s days. Maybe this will teach him his lesson."

Featured image: Facebook/Michelle Kirk

Have you had a similar experience?