Fill In The ______*

In the future everything will fly, except:

a) cars
b) pigs (an oft-referenced harbinger of a specific future instance)
c) common flies
d) time

The answer is D, as for many the future holds little promise of fun.
*
a) cavity
b) blank
c) porn star
d) all of the above

The answer is D, as all voids must eventually be filled.