Yes, I see the problem. Here is one solution, hacking the DropMenu snippet:
In five places replace the $pre with the following:
$child['description'] .' - '
(the .’ - ’ part is just to make a space of some kind, put whatever you like)
In my copy, it was lines 135, 236, 244, 245, 251.
I am sure that there is a way to pass someting in via the &pre= option, maybe using variable variables, but I wasn’t able to figure it out.
You should probably rename this hacked version of the snippet so it doesn’t get mixed up with regular menus.