Cold showers

Cold in general makes your penis smaller, yes. But that is only for a moment. Once your body is warm again, everything will be back to normal.

If you mean that if it makes your penis smaller for the rest of your life, no.

 

Biology bro!
See the thing is that our scrotum is for keeping our testes 2.5 degree Celsius cooler than our body temperature . So if its hot outside , it will hang more outwards and in the opposite case when the temperature outside is cooler than our body it comes closer to our body i.e. shrinks.
The penis size mainly depends on the blood flow towards it. If it's more it will tend to increase in size and may even get erect. But if the blood flow is less than normal, then it will shrink in size.
Cold showers, in my opinion tend to decrease the blood flow towards your penis temporarily by contracting the blood vessels and therefore you see as shrink-ed but when it gains temperature the blood flow becomes normal and it becomes of normal size.
Tip- Never walk out of cold shower naked in front of your girl or any visitor , may for wrong impression and cause future embarrassments.

 

Cold showers are the best, Say it or not warm showers are ok, they have average benefits but i have heard cold exposure to the penis is actually good for it.