Even a worm will turn

This page is about the saying "Even a worm will turn"

Possible meaning:
Everybody will revolt if driven too far. Even the lowest of people, or animals, will revolt and hit back at some stage. Even a worm, the simplest of animals, will defend itself.

Note:
worm (noun) = small thin animal with soft body and no bones or legs; turn (verb) = revolt, fight back