Crossed a line with this "trans" bullshit.

Lily • 💕20 and pregnant with our first baby! I'm a bit of a princess at times💕
Now listen up - people can be trans and I have no issue with it. I have a friend who's little brother used to self-mutilate his penis. The doctors diagnosed him with autism but also said he showed the signs of gender identity issues and the parents should be aware of this. He was only 4 or 5 at the time. We all took is very seriously even at his young age and didn't tell him he should conform to any gender-specific toys, clothing, etc.  
 
My issue is with parents that think it's some sort of trend or at worst, a joke.
At our local breakfast spot, a little boy came up to pet our dog. As a kid does, he fired off questions asking us everything about her. He then chats to us about cats (his fav animal) and THEN goes on to say.
"People think I'm a boy, but I identify as a cat - meow!" The mother sheepishly and sarcastically says "Yes, he carries around a tail" and clips on his tail. "He is trans-SPECIES".
This to me is just indulging a child's play fantasy in a way loads of people struggle to have their gender identity taken seriously. It's demeaning to what so many people fight for.  
(Unable to dress certain ways at work, with friends or in society)  
It's like when being homosexual was seen in a similar light and people had to fight for their rights as same-sex couples. Imagine a child at three or four saying "I'm a lesbian" because they think it's funny.
To be clear - I fully hold the PARENTS responsible for not properly explaining these topics to their children or explaining that saying these comments when not fully comprehending the issues simply isn't appropriate.
It's insane that parents aren't educating their children on the real world hardships these people face. 
It isn't a trend or some pretend game for your child to play. Explain that to them.