I remember these from my childhood:
The reply to Warum? “Why” was not a “nonsense answer”, but a rhyming counter-question Warum, warum, ist die Banane krumm? “Why, why, is the banana curved?”
The answer to “What do we eat?” was Kleinkinderfragen, mit Zucker bestreut “Little children’s questions, sprinkled with sugar”.

http://languagehat.com/because/#comment-1633146

 

I remember when I was a child asking my grandpa “Why?” and him responding “Therefore.” then commenting “That worked better when I was a boy and we used to say ‘Wherefore?’.”. I’m not sure whether it really was something he used dialectally when he was younger though, or if he was just jokingly implying he was of Shakespearian age.