[Pirate]

That is a point that we frequently try to make to some of our younger members (ahem): you can grow yourself out sex partners. In other words, you can make your penis so big (in length, girth, or both) that very few partners will want to have sex with you.
That being said, except in extreme cases, two people who want to will find ways of having sex, even if it is some form of "non-traditional" sex, if they are, um, motivated.
Even so, there are a lot of guys that are so insecure that they are willing to take that risk rather than have someone make fun of their penis again. Note that a hurtful penis remark can come from a male or a female (or the guy's own imagination for that matter.) There are some horribly mean people out there.