Where can I watch "Boku no Pico"? I heard from my friend that there is this anime called Boku no Pico and he said it was really nice. However, I can't find it anywhere online.

Is it legally streamed somewhere online?
You can purchase the Boku no Pico dvd bundles on Amazon or eBay. Due to search history at office I will be not providing urls for this.

You can also google streaming services for yaoi hentai that provide the episodes, or simply just google Boku no Pico. Once again due to search history at office I can not provide urls for this. There are plenty of legal streaming services that can be found on google for yaoi hentai. I also recommend looking up the definition of yaoi hentai incase you aren't aware about the meaning.

Incase you are an innocent one, please be advised to watch this while fully being aware that your friendship might be ruined after 5 minutes (if not less). I also do advice not watching this at public places or places with other human beings. 

Incase you know what you are looking for... have a good one.