A social games creator has filed a lawsuit against the makers of a ‘sex matchmaking’ app over the use of some of the same words in its title as the developer uses for its own games.

Games studio Zynga owns Words With Friends and Chess With Friends, and is taking legal action against Bang With Friends, which says it has more than a million registered users.

The app launched in January and notifies Facebook friends who express interest in a sexual encounter with each other.

Zynga has filed court papers in San Francisco complaining of trademark infringement, claiming Bang With Friends abuses the moniker it uses for its own products.