How do you say "F.U." using only your hand?
(OK, Aunt B, if you haven't already, you may want to navigate away from this page right now. It ain't purty.)
Depending on where you're from, it varies. Below are a few versions I've learned and used.
The first is "the finger" or "the bird." This is the one I learned growing up in New York.
This variant on "the finger/bird" is one that was more common when I moved to the South. It still looks weird to me, and is hard to do. Note how the forefinger and ring finger "bracket" the middle finger; this is allegedly a more "anatomically detailed" version of the non-verbal message this gesture is sending.
You can't watch British shows like Blackadder, Red Dwarf and The Young Ones without learning the "up yours" two-finger gesture. Turn your hand palm out, and this becomes the WWII British rallying cry, "V for victory," or the "peace" sign.
And finally, just to show I don't use my hands solely to make obscene gestures, here they are behaving themselves. This is what years of "soaking in it" will do for you.
Of course, there are many more obscene gestures. I think the Italians have cornered the market on them. But they involve more than just the hand.
I am curious to know if version 1 above is understood outside of the US, if version 2 is really regional US, and if version 3 is used outside Britain.