[MrsEmmaPeel]

I hate it when that happens, whatever it is.

I know what Jaffas are - they are a chocolate spherical candy with a thin orange flavored crunchy crust. Quite good. (That is, if you like an orange/chocolate combo.) Jaffa cake -- orange/chocolate cake? Dunno. Just guessing.

[alnitak]

What you have described *is* a Jaffa cake; Jaffa is just a shortened version.

A jaffa is also a seedless orange.

A jaffa is also a cricketing term, for a ball that is pretty much unplayable, perhaps because such a delivery is considered "juicy" - see orange.

BTW, The expression means to take the mickey.