If you've been on Twitter, Instagram or Facebook over the last day or so - or received an odd message on WhatsApp - you'll have noticed that there's a lot of strange pictures floating around.

If you've been caught on the hop by a picture of your mate looking particularly rough, and have checked that they're not hungover, it may be because they've Faceapped themselves.

Just like the recent 'baby face' filter on Snapchat, Faceapp's 'old age' filter has been sweeping social media with some very amusing results.

A number of celebrities have even joined in the fun, including the Jonas Brothers, while others have used it on pictures of figures like JFK and Bruce Lee with eerie results...

However, others have warned users to beware of what they're signing up to when they use the app...

So in short, download it by all means - but be aware of what you're giving it permission for.