I'm a total noob at Javascript and need some help!

A client of mine has asked for a dropdown menu, but in which the dropdown only shows onclick. However I have no idea how to go about doing this.

I have some experience creating Suckerfish dropdowns so am hoping I can use a little extra Javascript with it to trigger the dropdown.

I would prefer to do the dropdown with a regular :hover effect, but my client is quite insistent that it must only appear onclick.

Thanks for your help