eldersplain 

When an older person tries to explain to you (verbally) how to do something that you don't particularly need explaining to do. Particularly inappropriate behavior if the elder person is not related or even known to you.

The old lady went to "eldersplain" to me that I should just go to the front of the line and not worry about social-distancing because it isn't real anyway.

eldersplain by Myche September 15, 2020

elderslang 

Being able to communicate one’s past experiences to a much younger audience whom will most likely not understand what you’re talking about due to their complete inability to comprehend complex concepts

My dad and his friends were speaking some sort of elderslang or something. I don’t know what it was. They are old.

elderslang by El Jefferson February 1, 2023