Don't worry, it's not rude...in fact it made me laugh.
In the car yesterday I was telling dh about SenoraPostrophe's dd's ear and her emergency operation. I didn't realise ds1 was listening intently in the back..
Ds1: Who had to go to hospital? Was it M [a friend's little girl]?
Me: No, sweetheart. Not anyone you know. Someone who I talk to on the computer - her little girl was poorly. I don't really know her..well I sort of do..but I haven't met her...
Dh: One of Mummy's pretend friends, mate.
Men! They just don't get it, do they?