Too bad they won't make something you could drink?
They will!
Prickly Pear Ale
http://bindlestiffbeer.blogspot.com/2008/06/prickly-pear-ale.html
and
From:
How to Cut and Prepare Prickly Pears | Simply Recipes
I myself prefer just the juice. To extract the juice, place the "husked" prickly pears into a blender or food processor and pulse until liquefied. Place the juice into a fine mesh sieve and push out the juice into a pitcher or bowl. Discard the remaining pulp and seeds.
Use the juice as you like. About four prickly pears will get you about 1 cup of juice. It's great mixed in with some fresh lemonade, just use equal parts of prickly pear juice to lemonade.