At first glance, it might appear that the Xbox 360 and Playstation 2 consoles have quite enough buttons, over 11 at last count (which is more digits that most people have on all of their hands combined). But, what you may not know is that the two control sticks are also buttons. Simply apply pressure to each of the sticks like you were pressing a button and, presto! You're rewarded with the clicking sound of a button freshly pressed.
Of course, what this will accomplish will be determined on the game and whether or not the developer actually knew that these were buttons that could have functions assigned to them. So give it a try and see what happens!