Many people are fans of female-voiced virtual assistants such as Siri; some may even say they love them. But there are an increasing number of lonely individuals who have formed an infatuation with these AIs and are turning to them for companionship and "sexually explicit" conversations.

That's the opinion of Ilya Eckstein, the CEO of Robin Labs. He told The Times that Robin - his company's own virtual assistant - was being used by some people an excessive amount of times each day, and often for the kind of conversations you shouldn't be having with a machine.

"There are guys who talk to Robin 300 times a day. This happens because people are lonely and bored. It's mostly teenagers and truckers who don't have girlfriends. They really need an outlet," Eckstein said. "It's a symptom of our society. As well as the people who want to talk dirty, there are men who want a deeper sort of relationship or companionship."

Eckstein said that around 5 percent of conversations with Robin are of an explicit nature, while a third of interactions with the AI take place for no reason - users just want to talk to 'someone.'

The strange practice goes beyond teenagers trying to get a machine to talk dirty (there are entire YouTube videos dedicated to it), or long-distance truckers desperate for a conversation - even one involving an AI. Eckstein said there are those who use the virtual assistants to act out their fantasies.

"People want to flirt, they want to dream about a subservient girlfriend, or even a sexual slave. It may just be more for laughs, or something deeper underneath the surface," he said.

Microsoft's virtual assistant, Cortana, also has to fend off its share of unwelcome advances from lonely men. Speaking at this year's Virtual Assistant Summit, Deborah Harrison, one of the AIs writers, said that "a good chunk of the volume of early-on inquiries" were about Cortana's sex life.

Humans forming intimate relations with machines has been the subject of many TV shows and movies, and as technology becomes increasingly advanced and AI more human-like, it's not surprising to learn people are using virtual assistants for more than just restaurant bookings and directions.