If you have only oral sex with a guy, can you still get hpv?

the kind that gives girls cervical cancer?
and the girl giving the guy oral sex

Yes, but in that case it doesn't lead to cervical cancer. It slightly increases your chances of throat cancer:

http://cancer.about.com/od/hp1/a/hpvthro...

Oral-genital transmission of the virus is much more rare but yes, it is possible and has been shown to happen. I would strongly urge both partners to get tested for HPV before being sexually active. HPV has now been found to be linked to other forms of cancer besides cervical, cancers that both men and women are susceptible to.

If the guy has HPV in his genital areas then, Yes genital HPV types can be transmitted to the oral area. Your dentist can do a test and look for precancer changes in the oral area. Your dentist plays an important part in finding and treated cell changes of the mouth.

More information:
There are other forms of HPV which are sexually transmitted, and are a serious problem. The most common of these are; HPV-16, HPV-18, HPV-31, and HPV-45. These cancer-associated types of HPV's cause growths that usually appear flat and are nearly invisible, as compared with the warts caused by HPV-6 and HPV-11. (A scanning electron microscope image of one human papilloma virus appears at the top of this page.) Two types of genital tract HPV in particular, HPV 16 and HPV 18, are known to cause the vast majority of cervical cancers, and new studies show that they also linked to oral cancer as well. In the oral environment these manifest themselves primarily in the back (posterior) regions such as the base of the tongue, the oropharynx (the back of the throat in the mouth), the tonsils and the tonsillar pillars. These oncogenic or cancer causing versions of HPV are also responsible for other squamous cell carcinomas, particularly of the anus and penis.
It has now been established that the path that brings people to oral cancer contains at least two distinct etiologies; one through tobacco and alcohol and another via the HPV virus, particularly version 16, though other versions of the virus might be implicated as the research unravels further. The anatomical malignancy sites associated with each pathway appear to also be different from each other. In the broadest terms they can be differentiated into these areas; HPV related appear to occur on the tonsillar area, the base of the tongue and the oropharynx, and non-HPV positive tumors tend to involve the anterior tongue, floor of the mouth, the mucosa that covers the inside of the cheeks and alveolar ridges (the ridge area in which the teeth reside

http://www.oralcancerfoundation.org/hpv/...