McDonald’s Japan allegedly designed special straws for milkshakes, to mimic the pace and experience of breastfeeding, according to RocketNews24.

Backing up this claim is a book called Den Fujita’s Business Strategies 2: Overwhelming Business Strategies, one book in a series written by McDonald’s Japan founder Den Fujita, who died in 2004.

Fujita writes, “When humans drink something, the speed that produces the most delicious feeling is the speed at which babies nurse … McDonald’s straws are designed so that when used with a shake, the speed will be the same as that of an infant drinking breast milk.”

The below image features the McDonald’s Japan straw, though not in a branded McDonald’s cup:

Image: McDonald’s Japan

The book is not new. But after Twitter user @ritsu_mmsh tweeted out this factoid, the Internet responded in surprise. Despite the unique design, apparently the fact is not widely known.

もうシェイク素面で飲めない pic.twitter.com/ySZCo68Pbn

— 田殿はﾂｲ減したい (@ritsu_mmsh) September 21, 2015

It’s unclear if the straw is exclusive to Japan or used worldwide. Mashable reached out to McDonald’s Japan for comment but none was received by the time of publication.

So the next time you find yourself calmed by slowly, luxuriously sipping a milkshake (at least in McDonald’s Japan), you’ll know it’s intentional.

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