Users of U.K. dating app Happn must have been pretty confused last week when they opened the app to find just one dating choice -- a somewhat creepy-looking guy called Mark -- repeated throughout their timeline.

"Mark" was in fact a composite face concoted as part of a stunt by children's charity Plan U.K. to highlight the issue of arranged marriages for children, targeting Happn's more than 400,000 users in London. When users tapped on the fake "Mark" profile, they read a message that said: "When we're free to date whoever we like, it's hard to imagine only having one option. So whether you like Mark or not, he's sticking around."

JWT approached the charity about the takeover. Creative team Will Brookwell and Will Helm said in a statement: "The more we read about the issue the more we wanted to find a way to reach others. We realised that the best way to talk to people about lack of choice would be in the place where they have the most freedom, modern dating apps."

Plan's work revolves around helping young girls in developing countries; previous stunts by the charity have included an outdoor ad that was only viewable by women.