The most offensive has always been the 'okay' symbol we use in most of the world, but it is offered up usually with the back of the hand toward the one to whom you are being hostile. It has a similar connotation to 'flipping the bird' in English, but it refers to the a-hole...
In recent years, with the anglicizing of the world, flipping the bird is also offensive there.
If you make the Okay gesture with your hand, that is offensive to a Greek, referring that you're saying that they are part of the male genitals.
I think your question is missing some words. But don't ever give Brazilians the American "Ok" hand sign. It's like the finger over there. Image: http://www.istockphoto.com/file_thumbview_approve/3457192/2istockphoto_3457192-business-man-doing-the-ok-sign.jpg Actually, it is offensive only when displayed with the back of the hand to the person, usually with all three fingers together, and usually not with a big smile on your face, like the image linked above.
the hand gesture is a torch.
The hand sign 'F' is commonly used as an offensive gesture meaning "F*** you" or "up yours." It is considered vulgar and disrespectful in many cultures and contexts.
The most common hand gesture is the "wave," signalling or saying hello to someone.
To flip someone off in French, you can use the gesture of raising your middle finger while keeping your hand closed. This gesture is considered rude and offensive in many cultures, including France.
He used a common hand gesture to summon a crab.
The meaning of the open hand gesture is very simple. It means that the individual doing this particular gesture is denying, negating, interrupting, or stopping something that a person has said.
The shocker finger gesture involves holding up the index and middle fingers while bending the others and is considered a crass and offensive hand gesture meant to express sexual innuendo. It is not appropriate in most social or professional contexts.
reaching out his open hand and closing it into a fist
I used a hand gesture to tell the man to come over here.
An air quote is a physical gesture, a hand gesture resembling a quotation mark.