whyever

Why ever: an emphatic form of why.

Whyever would someone do that?

For whatever reason.

You can use it whenever you want and whyever you want.

Whatever we do, and whyever we do it, does not every motive originate in self, and does not every act proceed out of the individual's instinct for self-fulfilment ?

Regardless of the reason (why).

I don't care what you want. Whyever you're here, please go away.