Can you get an std from the penis hardly entering the vagina? my friend has a dull burning sensation in the opening she is also on her period.

Yes: Yes, and yes! sometimes there are stds in the secretions that come out prior to ejaculation(along with an occasional sperm!) and also if the penis has an std that he might not be aware of on the outside of the penis he can still shed it and give it away during close encounters. So both stds and less commonly but still possible, pregnancy are possible without actual penetration. Practice safe sex.