Wiktionary
why not
adv. 1 Why is that not true? 2 (non-gloss definition: Used to state that one has no objection to and approves of a proposal). 3 (non-gloss definition: Used to introduce a proposal).
Wikipedia
Why Not (song)
"Why Not" is a song recorded by American singer Hilary Duff for the soundtrack of the 2003 comedy film, The Lizzie McGuire Movie. It was written by Charlie Midnight alongside the song's producer, Matthew Gerrard.
Why Not
Why Not may refer to:
Why Not (George Cables album)
Why Not is the debut album by jazz pianist George Cables, released in 1975 on Why Not Records.