I'm translating a script for a cartoon into English. In one of the scenes a grandpa's talking to his granddaughter. It goes something like this:
Indeed! I have forgotten! Apparently, your grandpa’s getting a bit long in the tooth. Anyway, would you give your old grandpa a hug?
She turns around slowly. She sees her grandpa with long teeth. She rubs her eyes and the vision’s gone.
Seems clear, right? The thing is in my native tongue we don't say "long in the tooth", we say something along the lines of "be like a mushroom" (= be old). And, unfortunately, that's what you see when you're watching the original episode - a grandpa covered in mushrooms (not with long teeth).
As there's no way the producers are ever going to agree to change the original scene and make it work for the English audience, I need to come up with an idiom combining old age and mushrooms (a tree with fungi, possibly?)