not know B from a battledore

To be really stupid, or perhaps illiterate. The now-outdated term "battledore" was often used in reference to a children's primer. It was likely used in this phrase simply for the sake of alliteration. How do you manage to burn pasta? It's like you don't know B from a battledore.

Common Names:

Name	Pronounced	Usage
Caratacos	-	Ancient Celtic
Nona	['nəunə]
Vadimir	-	Russian (Rare)
Mared	-	Welsh
Vidar	VEE-dahr (Swedish)	Swedish, Norwegian, Danish, Norse Mythology
Harisha	-	Hinduism