I actually don't know what the whole "tail extensions" is about... I've never heard of it until like... Just now. lol
oh... well then 
*clears throat dramatically* in the episode in season 2 "Ponyville Confidential" the CMC's started spreading rumours about everypony to get their gossip column into the newspaper, because they thought that they'd earn their cutie marks that way. one of the rumours which was in fact true, was that Fluttershy had tail extensions
*clears throat dramatically* in the episode in season 2 "Ponyville Confidential" the CMC's started spreading rumours about everypony to get their gossip column into the newspaper, because they thought that they'd earn their cutie marks that way. one of the rumours which was in fact true, was that Fluttershy had tail extensions Ohh. I didn't see that one. 
haha no worries, you should! it's worth checking out :3
Aren't they all? 