Why is she going  so far? Why would she do that?
Panic and fear fills Gumball's eyes.
She is really going to do it, to her own son, she will be the one that will make his innocence evaporate.

Gumball's mother in a trance of fury, lust and passion. Forcing herself into her own flesh and blood, the creature she nursed and watched grow.
They can see their entire life together flashing upon their eyes.
All those bumps when gumball was learning to walk, learning to talk, all the struggles.
"I love you mom"
"you are the best mom in the world"
"thank you mom"
She cared for him, she did everything for him, she worked and sold her soul to a job that didn't respect her. She hated her job. But she did it anyways because of her family, for her son, specially her son.

A love, like only a mother can have for a child and she knew he loved her back. From Having him for 9 months inside her womb, for watching him grow. and that was enough for her to keep doing it.

But now...
She is throwing it all away, In a moment of uncontrollable passion.
she places the tip of her strap-on, a metallic dildo covered in spikes, that is thicker than a pringles can, and as long as one of Gumball's arms, all the way to his shoulder, on the entrance of her sons anus.
And she trust it inside him, all the way in , one swift move.
He wants to scream, the intense, unimaginable pain of his guts being stretched makes him want to scream like he has never had scream before, but nothing can come out, the gag has his mouth sealed.

The looks in his eyes, form fear, to panic, to complete desperation and pain, unimaginable pain.
A pain is so intense, that makes him wish for death... he wants her mom to just kill him instead, so he can stop feeling so much pain.

Nicole is just relishing on his son fear and agony, now, she doesn't care if she is hurting him or not, she just wants to ravage his ass, to punish him, to destroy his insides
.
She  rest her entire adult weight over her son sore ass, just for a minute, letting Gumball guts adjust to the giant torturous intruder. And then, she pulls out, in 1 move, like trying to turn him inside out.

Gumball is in shaking, he is crying, he is desperate. His anus gaping, his sphincter violated, his large intestine stretched beyond his limits.

His whole nervous system is about to collapse from the unimaginable torture, a pain that no mortal ever has experienced, and lived to tell the tale.
He is about to faint, but He doesn't. 
Because over all that overwhelming pain... all the physical suffering, the trauma from breaking every taboo imaginable, from his own mother defiling him...
a tiny spark of lust keeps him awake, hungrier for more. he is now, broken.

And that was, just 1 trust... So far.

Nicole, in a moment of clarity, ask him:
"I'm sorry, Gummball, I-i just don't know what took over me, just tell me and ill stop right now, because if I don't stop now, I won't be able to ever stop"
Gumball mind is on ecstasy, he cannot think straight... but in a second, his mind recovers.
"what ii happening? this is madness! she is going to kill me! i don't want to die! is not too late, it hurts so much, i don't wanna die! all i have to do is tell her and she will stop, i will die! i can save myself, all i have to do is tell her, and she will let me live"
Gumball now with his head completely clear is going to tell her to stop...
but he cannot talk, the gag is still in his mouth.
"it... IT WAS A TRICK QUESTION!?"
He panics his pleading screams for mercy are muffled.
he doesn't want this, he wants to run, but he cannot move, he is bound
he struggles
he uses all of his strength
he wants to escape
if he doesn't
it will be the end
"I see that you made up your mind then" Nicole worried look turns into an evil grin.
she gently strokes his head, and bends to kiss him in the cheek. a loving kiss, it represent all of their life as son and mother
but as son he mother lips leave his face, Nicole positions herself again, over his son butt hole.

He is no longer her son, now, He is just a toy.

She slams her hips down with brutal force 
Tears gushing down gumball eyes
A muffed scream comes out of gumball gagged mouth
He sobs uncontrollably, he cries, the pain is too much for a man or a beast, let alone a kid to handle
And Nicole pulls out again, and when just the tip of the metallic shaft is inside gumball
She slams again using exesive strenght.
Gumball struggles, the pain is just too much.
He cries but this doesn't stop Nicole
"this was your choice, gummypuss"
she repeats the motion, each time, she pulls out a little bit faster
and faster
after 20 minutes of accelerating, The brutal piston motion becomes a blur, almost hypnotic. Nicole virtually endless stamina means she can go for hours.

Gumball intestinal track is completely destroyed. He has never stop struggling for a second during this 4 hours marathon.
but his body is finally about to collapse, he lack the energy to move.

Nicole goes at him faster and more brutal than ever, using all of her strength, she wants to completely break her son. the phallic object stretching gumball's anus breaking past his colon, painfully expanding his intestinal walls and rearranging his lower digestive system. She brutally pistons on Gumball ass for hours and hours, doing irreparable damage to him.

it doesnt seems it will ever stop.

But at one point, Gumball, just stop feeling pain, he does not feel anything anymore.

Meals are a bit quiet now that Gumball is dead, But Nicole always remember with a smile, the 4 days of nonstop brutal pegging she enjoyed with her son.

the end.