On Mumsnet you can just go into settings and change your name to whatever you please without HQ involvement.
Because, er, reasons.
So you might start a thread saying
I've name changed for this, I have a massive boil on my bum and I don't know what to do about it^
and your regular buddies would not know that you had a boil-y bum.
Moths I had never seen before have appeared in my garden



