Scott crosses it in Chapter 18 when he almost rapes Dawn.
Tuerto crosses that line when he accepts the Cutie Mark Pool's essence.
Squick: In Chapter 11, the Total Drama gang is seen eating grass. In the world of My Little Pony, there are no bathrooms, no toilets... so, where do the cast go to the bathroom? In-universe reaction When that occurs to the Total Drama cast, they hastily spit out the grass.
The Woobie: Despite Chris' jerk tendencies, in later chapters, after realizing what he had was gone (losing Blaineley and putting the contestants in danger), he is at least attempting to be nicer to the contestants. Doesn't mean he'll pull the occasional prank every now and again.