This is driving me nuts and I've NC to post. My DS went to the zoo with his class last week. Came home with lots of stories and a new pencil and notebook. They had a really fun day.
A bit later via the class group text a message comes in from a parent saying thanks to the mum who anonymously phoned the zoo and bought them all a souvenir pencil and book.
For the next multiple hours there are messages from mum after mum after mum thanking this anonymously gifter. 
No one knows who it was. Then yesterday there was a note from the teacher saying thanks to the mum who anonymously did this.
AIBU to be weirded out by this. I mean, why do that? Why!!!