Casanunda, “the world’s greatest lover”, refers to our world’s Casanova. Notice that Casanova is often roughly pronounced as ‘Casanover’ (emphasis on the ‘over’), and that Casanunda (emphasis on the ‘unda’) is a dwarf…
Actually, Casanunda is lying, because we later find out he’s only the world’s second greatest lover. But this should not surprise us, since yet even later (in Lords and Ladies) we also find out that he is an Outrageous Liar.