Reading the comments to the news article 巴西女排变性球星将竞选国会议员 已瞄准东京奥运 about a Brazilian volleyballer who is transgender and wants to play in the Olympics, we have two comments:
Both use this term "JJ".
Can a male player cut a JJ to participate in a women's team? It’s really a mess! (Google Translate)
You can participate in women's competitions after jj. Is this fair for women's sports? (Google Translate)
Question: Is "JJ" slang for "penis" in Chinese?