While there are several reasons for a stench coming from your sex pistol, most are due to sanitary reasons.
"Any male odours down there have more to do with personal hygiene habits, rather than a medical issue," urologist David Kaufman tells Women’s Health.
Otherwise, a long day in tight pants or a tough workout can cause sweaty balls, and ultimately a rough smell just like any other part of your body.
"A guy who [eats] garlic followed by a full-court basketball game is going to sweat garlic."
However, if you've just jumped out of the shower and you notice your little friend smell a bit off, it could be down to infection - both sexually transmitted or inflammation and irritation.
If the tip of your penis is also red, it could be a sign of Balanitis, a common condition affecting 1 in 30 uncircumcised men. If you do notice the symptoms, it's best you visit a medical professional about treatment options - typically keeping the area clean and sometimes using steroid creams to reduce inflammation and a course of antibiotics.