To answer your question:
* Male guinea pigs have nipples, just like female guinea pigs. They are located along the underside of their body, from the chest to the groin.
* Nipples are not a reliable indicator of gender in guinea pigs.
* The best way to determine a guinea pig's sex is to consult a veterinarian or an experienced breeder. They can examine the animal's genitals to determine the sex accurately.
If you're unsure about the sex of your guinea pig, I recommend seeking professional advice from a veterinarian.