antonomasia
"I don't want to get involved with some Don Juan" (as a synonym for a heartbreaker)
or
"I don't want to get involved with a Don Juan"

Which one is correct?

Question

antonomasia
"I don't want to get involved with some Don Juan" (as a synonym for a heartbreaker)
   or 
"I don't want to get involved with a Don Juan"

Which one is correct?

Answer

Both are correct. "Some" means an indefinite "don Juan".

Answer

Ha-ha, I have some knowledge of the figures of speech, I suppose ;)

Answer

I had to look up "antonomasia".