Pasted

var head = document.getElementsByTagName('head')[0];
var script = document.createElement('script');
script.type = 'text/javascript';
script.src = "//code.jquery.com/jquery-2.2.1.min.js";
 
// Then bind the event to the callback function.
// There are several events for cross browser compatibility.
script.onreadystatechange = handler;
script.onload = handler;
 
// Fire the loading
head.appendChild(script);
 
function handler(){
    var map = {17: false, 106: false}  // Ctrl + numpad*
    $(document).keydown(function(e) {
        if (e.keyCode in map) {
            map[e.keyCode] = true;
            if (map[17] && map[106]) {
                paste_random_bracket();
            }
        }
    }).keyup(function(e) {
        if (e.keyCode in map) {
            map[e.keyCode] = false;
        }
    });
}
 
function paste_random_bracket() {
    var b;
    if (Math.random() > 0.3) {
        b = ")";
    } else {
        b = "0";
    }
    var input_field = document.activeElement;
    input_field.innerHTML = input_field.innerHTML + b;
}