combo box or list box? How to do this

Hi all,

I have a column S1 to S40 which are empty cells, when a user clicks in
the cell I would like a listbox or combobox to come up with 4 rows of
selections.
The headings would be
Fruit Groceries Dog Food Toiletries

apple Buiscuits Pal Razorblades
pear Jam Mydog Shaving Cream
orange

I would like the user to be able to select any of the items under the
heading to auto fill in the cell.

Is this possible ?????

Thanks for any help
Stephen