As nouns the difference between fanny and sanny
is that fanny
is (british|irish|australia|nz|south african|vulgar) the female genitalia or fanny
can be (uk|naval slang) mess kettle or cooking pot while sanny
is (uk|dialect) the sandpiper.
(en proper noun
* 1883 , Heart and Science , Chatto and Windus, page 227:
- "My name is Frances. Don't call me Fanny'!" "Why not?" "Because it's too absurd to be endured! What does the mere sound of ' Fanny suggest? A flirting dancing creature - plump and fair, and playful and pretty!"