trying to jump battery lights flash and horn blows

Another way to stop the horn from blowing, open fuse box and remove horn fuse. Connect battery , start car and reinstall fuse. Problem solved

When I was trying to remove cable of negative terminal of battery I forgot to lock car by remote then suddenly I touch negative cable to terminal of battery and looked car but it different sound but after charging battery when I first connect positive and then negative it started blowing siren..so I didn't connect negative terminal because when I m trying to connect negative terminal it started siren like as a someone trying to open door with different keys or say stealing..how can I resolve this problem?