Degrassi Season 11 can refer to two related things.
N; A Degrassi Season 11 is when a book/movie/TV show/series/etc. pulls off a fail of such massive proportions that its very reputation is forever tarnished and can never be redeemed. Common signs that a series has reached a "Degrassi Season 11" level of fail include (among other things) having guidos in it, having one or more Gary Stus, a Mary Sue, homophobic treatment of LGBT characters, and crappy acting.
While this term is similar to “Jump the Shark" , it is not the same thing. “Jumping the Shark” is the point at which a series has reached its high point and from then on out it’s downhill. A “Degrassi Season 11” is whenever a series has already hit rock bottom and from then on continues to get steadily worse and worse. Also note that whenever a series Jumps the Shark, it’s possible but unlikely that it will improve and regain at least some of its former glory. “Degrassi Season 11” is when it’s gotten SO awful that it would take a fucking act of God to turn it around.
However, at the same time, despite its obvious badness, there may still be a small following that clings stubbornly to the series former glory and continues to put money in the pocket of the people who ruined whatever it is. More frighteningly, there are some cult-like followers who may actually believe the “Degrassi Season 11” is of decent (if not better) quality. These people are also often unaware of what the show/movie/whatever was like when it used to actually be good. The people who fall into the latter category are typically characterized by an over-inflated sense of self-worth, an inability to put together a decent argument, bully-like behavior, and all-around fan-brattiness.
Person A: “Ugh, I just watched the NeverendingStory 3 for the first time.”
Person B: “Oh my god! That movie was SO bad! Why the fuck did they even make that if it’s not in the book?! It makes me wanna punch kittens.”
Person A: “I know, right? It was a total Degrassi Season 11.”
Person C: OMG!!11 THE NEVERENDING STORY 3 WAS THE BEST MOVIE OUT OF THE ENTIRE SERIES!!!1 On the other hand, I didn’t know there was a book of it.”
Person A and B: *together they slowly back away from this obviously deranged person*
V; To Degrassi Season 11 something/ pull a Degrassi Season 11 is to fail so massively that one’s failure could be compared to the above.
Person A: “Fuck my life. I just made a zero on my Spanish final.”
Person B: “Dude how could you make a zero?! We stayed up all night studying!”
Person A: “I guess it went in one ear and out the other. I guess I Degrassi Season 11ed it.
Person B: *shakes head at the epic failure.*