It wasn't until I heard Victor Borge do his 'inflationary numbers' act that I realised that Don Juan was not pronounced Don June.
But when you're reading the poem by Byron, you have to pronounce it Joo-wan:
I want a hero: an uncommon want,
When every year and month sends forth a new one,
Till, after cloying the gazettes with cant,
The age discovers he is not the true one
Of such as these I should not care to vaunt,
I 'll therefore take our ancient friend Don Juan
We all have seen him, in the pantomime,
Sent to the devil somewhat ere his time.
Regarding pronunciation, BIL considers himself quite the Spanish linguist. It still tickles me to remember him ordering 'steak Tampikwena' (Tampiquena, pronounced tampikenya). I'm not an expert in Spanish, but I believe the qu is almost always pronouced as a k - queso, que, tequila, etc. Add in a very heavy twang and it was pretty funny. Of course, MIL says 'kweso' for 'queso', so it's a family thing. Funniest part is, they live in an area with a large Hispanic population, so Spanish words and phrases are common vocabulary.