If you feel like handcoding it, this should do the job:
The html:
<div id="tooltip" style="display:none;">bla bla</div>
<div id="yourLink">Click here to show the tooltip!</div>
And the JS:
$('#yourLink').click(function(){
$('#tooltip').toggle();
});
You just need to style correctly the tooltip div
There are also nice tooltip plugins out there. iftrue mentioned one, there is also this one
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