I think humor is so important and keeps things in perspective! Laughter is the best medicine after all...
I am glad to hear your uncle is doing fine - he is lucky to have you. I am sorry to hear that your aunt is suffering from alzheimer's. That alone is tough enough without any additional health concerns. It sounds like she still has some spirit however.
I know when my father had aphasia which is a speech problem related to a stroke, it was hard for him to keep his spirits up. It is hard on the care-giver also!
I am lucky now in the respect that my 93-year old mother is well-cared for in a place of her choosing with no form of dementia or other health problems. TG for that!!!