STD? STD? STD? STD? STD?

Ok something has been bothering me greatly. I have a guy friend who is Straight and for a long time me and him have been making plans do....things.... and it was always his decision first. Each time this guy would blow me off though and make up some excuse as to why. But then he tells me that he don't like bi girls (which is what I am) because they might give him something. When I asked him about that again he said that bi girls can carry STDs (which I know) and are the most common because they do both sexes (which I think Is bullshit). But... Is this true?

Do people who date both sexes have a greater chance at catching a STD then people who only date one gender? (tthat'skinda my question)

I mean, I kinda think we all have the same chance at getting a STD depending on if you use protection or not. But could anyone direct me a web page that clearly states this is false or true so I could blow it up in this guys face. Umm...plz? anyone?