Viola Clef

11-yr-old viola student picked out a new piece.  A bit more advanced than her previous pieces, it included a treble clef.

Girl [pointing]: What's that?!
Me: That's a treble clef, you know about these.  You see them in music at school.
Girl: But what's it doing in my music???
Me: Well, it's just to stop us using, like, fifteen ledger lines.
Girl: But I just want the back-to-front three.
Me [slowly]: Vi-o-la clef.
Girl [stubbornly]: Back-to-front three.
Me: Viola clef.
Girl [posh voice]: Well, it might be ... that... in fancy-pants language, but I call it the back-to-front three.
Me: Vi-o-la clef.  Um... How do you write your threes?
Girl [pauses]: Oh.  Oh.  [giggles] How embarrassing.  I mean, a back-to-front 'S'.
Me [starting to giggle]: How do you write an 'S' then?
Girl [getting a bit flustered]: Um.  I mean.  Agh!  Just get it out of here!!!