I wouldn't really recommend misclicking as it could possibly mess something up, however moving the mouse too far or not far enough is easy enough.
Something like this you mean?
Simba Code:
procedure MmmDatAss(X, Y, RX, RY : Integer);
var
XX, YY : Integer;
begin
MouseSpeed:= 25 + Random(3);
XX:= X + RandomRange(-85, 85);
YY:= Y + RandomRange(-85, 85);
MMouse(XX, YY, 0, 0);
GetMousePos(XX, YY);
XX:= Round((XX + X) / 2) + RandomRange(-7, 7);
YY:= Round((YY + Y) / 2) + RandomRange(-7, 7);
MouseSpeed:= 10 + Random(3);
MMouse(XX, YY, 0, 0);
MouseSpeed:= 6 + Random(3);
MMouse(X, Y, RX, RY);
end;