Show 2 images?

Hey vegaspro,

You can do that on mouse hover using css sprites. Please check https://css-tricks.com/spriting-img/ and https://css-tricks.com/css-sprites/

You can change :hover to :active to make it work similar to onclick :)

To do it the jQuery way Please try adding this at the very end of your themes / child themes functions.php file:

function swap_img(){
?>
<script>
jQuery(document).load(function(){	
// Add your jQuery script here
jQuery("img").on('click', function () {
   jQuery(this).attr("src","new.gif")
})

});
</script>
<?php
}
add_action('wp_footer', 'swap_img');

Let us know if you have any questions.

Best regards,
Vinay