Rule Thirty-Vast

(AKA "Macro's Law")
Fan works are awesome! They allow artists to create works of their favourite characters and allow them to go on new adventures, albeit occasionally perverted.
We all know of Rule Thirty-Four: If it exists, some crackpot wierdo's made porn of it. Rule Thirty-Vast is similar, except replace anything with anyone and porn with altered size. 
As this suggests: If a character exists, expect to see them towering over cities or exploring a giant backyard. While this doesn't always revert to porn, expect to see macrophile works do this on occasion.
That being said, it isn't all sluts and butts. Most of the time this is done for fun, often giant heroes fighting crime or being cute or borrower-ised people just exploring around.
This doesn't just apply to humans (or at least, human-like creatures) though, animals (including anthropomorphic ones) and robots are also affected by this, so expect to see those too.
Not to be confused for "Rule 3-VORE", where it's "If a character exists, there's vore of it".
Be warned that this could result in sudden and violent behaviour changes if the writer or artist wants a more hostile giant.