Nintendo Switch Sports released last week and already the game is being flooded with inappropriate user names.
Nintendo has added a filter to prevent obvious rude words, but many players are finding creative ways to circumvent the filter.
Players on Reddit want Nintendo to amend the naming filter, or add a method of reporting inappropriate content.
"Honestly I hope this stuff doesn't catch on. I want this game to not be an absolute toxic cesspool with names that could be offensive. You see that in other games and ya, I hope the Switch Sports community stays wholesome," said one user.
Another user shared names referencing child sex abuse images, requesting Nintendo add a reporting function. And while some memes are amusing, they added: "I don't mind those kinds of names, I just don't want to see 'Intense Child Porn' on my Switch, or anywhere for that matter."
One user replied: "100 percent this. I saw some disgusting ones and all I could do was go in and block them on the Switch settings for recently played with users. It should be better than this and their filters need to catch more."
Obvious swear words have already been blocked by Nintendo. But often, simply inserting a number is enough to get around this.
The inclusion of Mii characters has also allowed players to get inappropriate content passed. Some Reddit users have reported playing against the likes of Bin Laden, Hitler, and Michael Jackson (with a child pornography joke).
We described the game as "a treat" both offline and online in our Nintendo Switch Sports review. But it seems Nintendo needs to up the safety of online play.
Eurogamer has contacted Nintendo for comment.