Mousover tooltips for text / "Blank" links

This is such a stupid question. I’ve been hand coding HTML since I was 12 years old and for some reason this isn’t coming to me at all. Forgive me.

I want certain phrases in my blog posts to have rollover “tooltips.” BUT I don’t want links… because they aren’t links. The popups are just little side snippets of thoughts.

So how do I make a “dead” link… if clicked it doesn’t go anywhere, just stays put on the page. Or how to I append alt text or a title tag to an inline block of text?