So, lets think this through a bit;
You're meeting up with a guy in one of two ways;
You met this person at work, at school, through mutual friends, at a party, or somewhere in public. You've gone out with him enough times (hopefully more than once) that you're both ready to do it.
At this point, he likes you enough to want to have sex with you, and while he probably isn't going to throw a parade celebrating your smaller penis, I have a hard time believing he's going to walk out of the room all J Lo style. In this situation?
That is how one finds out about the genitals of their partner- by finding out. Normally people don't converse about that as part of a sequence (step one; talk about self, step two; talk about family, step three; the past, step four; the future, step five; junk size, step six; where to go for dinner etc.)
The other way you're likely to be headed out on a date with a guy in 2013 is because you've used A4A or Grindr or some other app that hooks gay guys up for a litany of reasons. Those sites all have profiles that specifically allow you to list the length of your junk so there are no surprises.
Either way... it's my opinion that you're imagining this to be a much larger problem (no pun intended) than it actually is. In spite of protestations to the contrary on this site? There are
far more important things than the size of a guys cock.
JSZ