About Happy Banana
Two friends in New York read the polyester studies and could not un-read them. We could not find a boxer brief with zero synthetic fiber in the fabric. So we made it.
It started with a study.
In 1992 a surgeon in Cairo had 14 men wear a polyester scrotal sling for a year. Every one of them reached zero sperm count after about 140 days. It reversed when the sling came off, and their hormones did not change (Shafik, Contraception, 1992). A sling is not underwear. It still stopped us cold.
Then the newer studies landed. Microplastics in all 23 human testes examined (Hu et al., Toxicological Sciences, 2024). PET, the plastic polyester is made from, the most common plastic found in men's semen (Guo et al., Toxics, 2025). And a 2026 review admitting nobody has ever run the fabric study under normal wearing conditions (Zleczewski et al., Translational Andrology and Urology, 2026).
Then we looked at the shelf. Almost every pair of men's underwear sold in the US is some blend of polyester, nylon or spandex. Those are plastics, worn all day on the most absorbent skin a man owns.
So we built the alternative.
We sourced 100% merino wool at 17.5 microns. No polyester. No nylon. No spandex in the fabric. The waistband is a standard elastic waistband, like every boxer brief, and we say so. Made in China. Ships from New York City.
Merino regulates temperature, absorbs up to 35% of its weight in moisture while feeling dry, and resists odor because it manages moisture and its fiber surface slows odor bacteria. It is softer than any cotton you have worn. It is what underwear should have been made from all along.
Why “Happy Banana”?
Because your Family Jewels deserve royal treatment, and the name is honest about what we are protecting. The name makes you remember us. The science makes you stay. We are serious about men's health. We just do not take ourselves too seriously while doing it.
Our mission is simple.
Give men a real alternative to the synthetic fabrics that dominate the underwear market. No greenwashing. No “organic cotton” half-measures. Just the single best natural material for the job.
What we stand for.
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Science-First
Every product decision is backed by peer-reviewed research. We cite our sources because we want you to verify them.
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Plastic-Free Fabric
100% merino in the fabric. No polyester, nylon or spandex touching skin. The waistband is standard elastic, and we tell you that instead of pretending.
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Radical Transparency
We used to word our testosterone claim badly. We fixed it. We do not promise hormone changes or fertility outcomes. We remove one everyday plastic from the equation, and every claim links to the study, including the ones that do not go our way.
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100%
Merino Wool
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0%
Synthetics
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4.2 in
Inseam
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30 days
Money-back guarantee
Ready to make the switch?
Try a single pair risk-free. 30-day money-back guarantee, no questions asked.