What does it mean when someone makes a "C" shaped hand signal or gesture when driving (usually aggressively)?

Question

When driving on the highway, I moved in front of someone who did not want to let me into their lane. They then got in front of me quickly, braked hard, and held up their hand in a "C" shape - almost looking like a gang signal.

A few weeks later, my girlfriend came up behind someone driving very slow on the highway, and got close behind him thinking they would speed up. They got annoyed and gave her the same "C" shaped hand signal. Does anyone know what this hand signal means? They occurred during different situations, and to me, a male, and a female (so the usual C-words probably don't apply!).

Answer 1

sorry but i think they are calling you a cnut.

(swap u & n )

Answer 2

calling you a 'C' word. if your sure it doesnt relate... maybe 'careful' or caution or c'mon could be anything. thining the first one tho.

Answer 3

Sorry, But I think your right too. That was what came to my mind immediately!