It's just from a bygone era. Plus they use such high vocabulary!
"Oh, it's a jolly holiday With you, Bert
Gentlemen like you are few
Though your just a diamond in the rough, Bert
Underneath your blood is blue!
You'd never think of pressing your advantage
Forbearance is the hallmark of your creed
A lady needn't fear when you are near
Your sweet gentility is crystal clear!
Oh, it's a jolly holiday with you, Bert
A jolly, jolly holiday with you!"