function text() {
};

text = new text();
number = 0;

// textArray
text[number++] = "<img src='images/bubble1.jpg' alt='bubble1'>"

text[number++] = "<img src='images/bubble2.jpg' alt='bubble2'>"

text[number++] = "<img src='images/bubble3.jpg' alt='bubble3'>"

text[number++] = "<img src='images/bubble4.jpg' alt='bubble4'>"

// keep adding items here...

increment = Math.floor(Math.random() * number);

document.write(text[increment]);