var toggle = 0;
$('.thumb_img').click(function() {
if(toggle == 1) {
$(this).attr('src', $(this).attr('src').replace('img/full/', 'img/'));
var toggle = 0;
} else {
$(this).attr('src', $(this).attr('src').replace('img/', 'img/full/'));
var toggle = 1;
}
})