Serious post guys, this one’s about swearing. In particular this one’s about sweary hand gestures.
The picture at the top of the page is a peace or victory sign. First two fingers held up, palm out. It’s pretty common to see in photos these days, especially here in Japan. No problems. However, turn that sign around, so the back of the hand is towards the viewer and you have a really rude gesture.

At least in the UK, Ireland, Australia and New Zealand (maybe South Africa too?). It’s called the V-sign, or two-fingered salute, or forks in Australia. You can say give two fingers, flick the Vees, or show a v-sign.
Why? No one really knows. As it’s offensive to Brits but not Americans it might have developed after American Independence, the old story about English archers fighting the French is definitely not true.
Up Yours? When you make a v-sign you might also say ‘up yours’. The Cambridge Advanced Learners Dictionary says:
Up Yours! Offensive. Used to show that you very much dislike someone or the things that someone has just said or done
More about the v-sign, the peace sign and up yours, on this sweary blog.
By the way, if you hold your two fingers together that’s not rude. A bit strange but not rude.