age before beauty
- (idiomatic) A phrase said to allow older people to go before younger ones.
Usage notes 
Now most often used humorously or lightheartedly, and usually said by a younger person to an older friend or relative out of mock pity (for being so much older and unattractive -- even if such is not the case). In most instances it would be considered rude for a younger man to say this to an older woman.