I will probably be giving my first blow job soon to the boy I have been dating for the past four months. The farthest he had gone before me was making out, and has since reached second base with me. I know he is a virgin to both intercourse and fellatio, but I am wondering if I still should ask him to buy condoms to have in case we reach third. I know that he has not slept around or even ever had sex, but I wonder if there is still some weird risk or something that he could pass me an STD. I am a very paranoid, rather OCD person and I'm worried about this. I have done a lot of research and all the websites say that when performing fellatio, you should use a (flavored) condom, but none of them mention if this is necessary even if the people involved are both young and virginal. I would love some advice. Thank you.
The short answer is that yes, you should always use a condom in order to be as safe as possible.
The longer answer is that while being a "virgin" (and remember, since that's a social construction rather than a medical one, it is defined differently by different people) may reduce your risk, it does not completely eliminate the risks. There are STIs which can be transferred in non-sexual ways. Some may be passed from mother to child during birth or may be picked up from things like sharing towels. My favorite example that is particularly applicable to oral sex is that of oral herpes. Many many people have oral herpes that the got in total non-sexual ways (often when they were just youngsters) from sharing drinks or a kiss from a relative. While condoms don't completely prevent the spread of oral herpes to the genitals of a partner (or vice versa), they certainly do provide a great deal of protection.
So when it comes to any sexual activity, the very best thing to do is to use barriers like condoms and dental dams to be safe. In order to even consider foregoing the barriers, you should really have been monogamous for at least 6 months, with at least two clear STI screens (where you show one another the results printouts) for each of you during that period (and then you should both be tested at least once a year). Even with that 6 month period, there is still no guarantee.
It would be a good idea for you or your partner to pick up some condoms to use if you plan to be sexually active in any way. In fact, it would be a good idea for you to pick up some condoms as well so that you will know for sure that you've got condoms available to you when/if the time comes. While you can definitely ask your partner to pick up the condoms, it is always wise to have backups around in case a partner does not have any available at the time.
Here are a couple of links that may provide more information: