I offer a horrible crossdisciplinary (heraldic, historical, mathematical, and vexillogical) pun that came to me on the way to work one morning.

Q: Why is the flag of Libya equal to the city of Istanbul?
A: Because it's a constant sinople!

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On a related note, I present also the following blazon, which is of course several kinds of broken — but isn't it worth it?

Sable, semy of stars silver, a Space Shuttle suspectant of the same [streaming a swash sanguine and] surmounting a sphere sinople and sapphire; and to sinister, a second sphere, smaller, Sol.

The swash sanguine specified in square brackets is supposed to be streaming behind the Shuttle as it travels in its notional orbit — vaguely like the Nike swash, if perhaps more symmetric; there are a number of examples of this sort of thing on actual Shuttle mission patches. (On any spaceflight program's patches, actually.) While the remainder of the blazon is clear (albeit painfully contrived), I'm not sure that I can reasonably expect the bracketed part to be comprehensible to anyone who hasn't seen the (so far, strictly hypothetical) device, or at least has a reflexive familiarity with spaceflight mission badges.

(... why, yes, I did want to be an astronaut when I grew up. How could you tell? ^_^;)