Boners are all about blood flow. So your heart—the organ that pumps your blood—has to be in tip-top shape for you to have A-plus erections. Anything that puts strain on your ticker, like being overweight or smoking, also tends to take lead out of your pencil.

Testosterone is the second factor that's crucial to a strong erection, and there are plenty of weird things that screw with its production. All the items on this list can mess with your manhood:

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