Because

Just learnt that regardless of what grammer might dictate, a sentence can begin, end and comprise solely of one word: 

"Because!"

Scientific observation: There's usually an exclamation mark at the end of such a sentence as well. 

Illustration: 

Whenever we get back home from outside and are barely inside the garage door, the first thing Miss Haana wants to do is take off everything she thinks she can. On one such occassion, it was cold and rainy outside. We had barely stepped back inside the home. She already was taking off her boots and was tugging at her jacket to get it off of her. 

Then she said she's wants her socks off. I said, it's cold so keep your socks on. The floor is cold.

She said, no, she wants the socks off.

I asked- why?

And there it was- her reply was:

"Because!"

The socks came off.

I was knitting my eyebrows.