Here is a story I wanna share with you:
There were no words about genital organ appearing in my English studying book. Meanwhile, I seldom read materials (in English) about sex before. What I know are words like: p***s, v***a, p***y and d**k. That resulted in a hilarious story:
In the kitchen, my flatmates (all non-Chinese) and I were having dinner together and I didn't recall why they mentioned the word - testicle. I didn't know what it means..and asked them what it is. They (boys and girls) explained that the balls between my legs. OMG...What a embarrassment on me! I did want to dig a hole on the ground and get into it. AH AH.......
So..as an English learner, you'd better learn English from all aspects!
One of my friends told me: In English speaking countries a penis can also be called a member or a Johnson. So if somebody says: can I introduce my friend, little Johnson .. Do not be surprised with howls of laughter!