To an Older Coworker: “My grandpa gave me that same advice.”
Your older coworker is not your grandpa. In fact, he might not even have grandchildren, which would make this comment especially irritating and offensive.
Think of the connotations of grandparents. In popular culture, they’re mostly depicted as old-school, not as physically capable and suffering from some sort of dementia. This comment implies that your coworker’s advice will always be outdated and out of touch with reality.
Older nurses are usually sensitive to age as a topic in general, so skip the grandparent talk altogether. If your coworker gives you advice you’ve heard before, just say “I’ve heard that advice before!” Just don’t specify that your grandpa gave it to you.