I ❤ firefly
Here is the long answer, if you take super length anal toys, there is a bend you have to get passed. How far is different for different ppl and body types. You can get away w/fucking really deep like big cock deep without getting passed it and it'll just kinda hurt more, but at a certain length like 10-12 inches and over, you're not going to be able to take it without going passed it. It's difficult and freaky at first, and you could hurt yourself if you don't use something flexible to condition yourself. However, you can condition yourself to where it's easy. What's happening is your colon actually straightens up.
A porn girl who regularly takes really long toys got a colonoscopy and tweeted that the doctor said to her, "You have an unusually straight colon." So it's absolutely a real thing, and you can plainly see how straight the girl in that gif is.
If you stop taking long toys for long enough, your insides will go back to normal, and it will once again be really difficult to take anything super deep.