MyCode For Thread Subject?

[ReCaptcha]

Hello,
is there a mycode that will show the thread subject for example

I write:
Hello the thread subject is: [SUBJECT]

and it Displays:
Hello the thread subject is: MyCode For Thread Subject?


I tried a few things but nothing seems to work :'(

I know(guessed) i could make a simple plugin for this but i really don't want a plugin just for a mycode...

Any ideas?