I run it with DNA and I got few RNA smears, so I would like to whether it's RNA or something.
which protocol are you following kit based or TriZol? I would suggest you to try Trizol method which gives good quantity and quality of RNA.
The isolation of spermatozoal RNA is a challenging procedure due to the intrinsic heterogeneous population of cells present in the ejaculate and the small quantity of RNA present in sperm. The transcriptome of these gametes includes a wide variety of messenger RNAs (mRNAs), small noncoding RNAs (sncRNAs), and highly fragmented ribosomal RNAs (rRNAs).
sending you a reference link, where you can get both manual and semi-automated experiment, with preference given to automation for consistent results.
http://link.springer.com/protocol/10.1007%2F978-1-62703-038-0_33
You mentioned you run it with DNA? so, what's your goal here? If only study DNA, you can simply add RNase. If you're interested in study sperm RNA, then there're different types of RNA as Jagadish mentioned, then what type of RNA you want to study? that will influence how you extract it, unless you want get total RNA from sperm.