Some people may think this joke is only funny to "senior citizens." I think not. My parents heard it at an elder hostel in New Mexico this summer.
Seems that this old couple are having trouble remembering things, so they sign up for a memory course. The course is wonderful; they come home and tell all their relatives, friends, and neighbors about it. Some months later, a neighbor approaches the man as he tends the garden.
Neighbor: Say, Ed, what was the name of the instructor of that memory course you liked so much?
Ed: Well, it was...hmmm...let me think a minute...
What's the name of that flower, you know, the one that smells so nice, but has thorns on the stems...?
Neighbor: You mean a rose?
Ed: Yeah, that's it...(shouting toward house) Hey, Rose, what was the memory course instructor's name?