If you’re one of the millions of moviegoers who’ve seen “Mission: Impossible – Dead Reckoning Part One” in theaters, two thoughts likely crossed your mind as you wolfed your popcorn in the air-conditioned dark: 1. Wait, is that really Tom Cruise riding a motorcycle off a cliff? (Yes!) and 2. How does the man look so damn good at 61?

Turns out, Cruise’s skincare secret might be a crock of s—t: For roughly a decade, reports have credited the actor’s ageless glow to powdered bird poop, or what the Japanese call uguisu no fun.

“Tom doesn’t go in for Botox or surgery, but he does pay close attention to all the new and popular natural treatments,” a source close to the star told Now magazine in 2012, per HuffPost. “He recently started experimenting with the nightingale poo facial.”

Dr. Melissa Kanchanapoomi Levin, board-certified dermatologist and founder of Entière Dermatology, tells Page Six Style the use of uguisu no fun in skincare dates back to ancient Japan.

“Geishas and kabuki actors in the 18th century used nightingale droppings to remove their heavy makeup and whiten their faces. The droppings were found to have naturally high levels of urea, which helps retain moisture in the skin, and guanine, an amino acid that imparts a luminescent quality to the skin and fights sun damage,” she says, adding that some proponents of the fecal facial even claim it can clear acne and minimize pores.

Cruise apparently experienced “fantastic” results from the treatment, which was “recommended by a Hollywood pal” — perhaps David or Victoria Beckham, who also reportedly incorporate avian dung into their skincare routines. And considering his face has hardly aged in the decade since, I had to try it for myself.

My mission, should I choose to accept it? Incorporate bird poop into my skincare routine for a full week in hopes of turning back the clock, Cruise-style.

Select spas offer these so-called “geisha facials” for hundreds of dollars, but after a bit of Googling, I discovered you can purchase a bottle of pure Japanese bird poop on Amazon.

Uguisu Poo’s Uguisu No Fun Illuminating Mask retails for just $45 and boasts a decently respectable 4.2-star rating, with shoppers describing it as everything from “my new favorite product” to “smells like a barnyard.” I held my nose and placed an order.

Uguisu Poo Uguisu No Fun Illuminating Mask ($45)

A double-duty (or rather, double-doody) buy, the powder can be both added to face wash for an extra dose of exfoliation or mixed with warm water and applied as a mask — and no, not like the eerily realistic kind Ethan Hunt wears to impersonate others and execute his missions. I figured I’d use it both ways each day for good measure.

Uguisu Poo touts its hero product as “UV sterilized and purified to remove musky odor,” and indeed, it’s entirely scentless straight out of the bottle. That said, it took on a decidedly off-putting aroma when rehydrated — stale and a bit sweaty, like Cruise’s socks might smell after one of his iconic “M:I” sprinting scenes.

This meant my husband, whose nose is stronger than mine, didn’t want to come anywhere near me during the 10 or 15 minutes it took for my nightly poo masks to dry. (My bird-obsessed cat, on the other hand, didn’t seem to mind one bit.)

Smelliness aside, however, the uguisu delivered decent results for an over-the-counter product; after each mask, my face felt soft and smooth, if not exactly de-aged, and my pores seemed ever so slightly smaller.

But while beauty buffs shouldn’t pooh-pooh this time-tested treatment, Dr. Levin notes that “not everyone may experience significant benefits” and there are potential risks worth considering — particularly when it comes to hygiene.

“The droppings come from birds and may contain harmful microorganisms,” she says. “To mitigate this risk, reputable spas and manufacturers follow a process of UV sanitation. However, some individuals may still have allergic reactions or skin sensitivities to the components in uguisu, so it’s essential to do a patch test before applying it to the entire face.”

And ultimately, there are plenty of other ingredients — from retinol to niacinamide to hyaluronic acid — that can offer similar (if not superior) results.

“While there may be some benefits to this ingredient, there are a lot of [others] that also help to exfoliate,” Dr. Marisa Garshick, a board-certified dermatologist in New York City, tells Page Six Style.

“So if you’re hesitant to use nightingale droppings on your face, you can feel reassured there are other ways to get brighter skin.”

As for me? While my skin didn’t self-destruct like one of Hunt’s IMF messages after a week of being slathered in poo, I’d rather spend my money on prescription topicals.

If I’m going to age as well as Tom Cruise, after all, I suspect I’ll need something a bit stronger than nightingale scat.