Showing custom field data

I need to be able to embed links in posts and pages which, when clicked, reveal more information. I’m storing the extra text in custom fields. I’m looking for a method where I either:

1) Click the link and have the custom field text appear, pushing down the text below it; or
2) Click the link and have the custom field text show in a pop-up window.

Method 1 is preferred 🙂

Can anyone suggest a plugin that might do stuff that that or suggest another method to achieve that functionality?