Back in the day, when my school had early fall recruitment, we were allowed to have summer rush parties. So we actually got to meet PNMs, before rush, in a more fraternity-rush-like setting - for example, we'd have a picnic in Central Park in NYC and on the Esplanade in Boston. (Unfortunately, this meant that if you, as a PNM, didn't live in or near a major city with enough active sisters to host a party, you were SOL.)
There was also a good amount of "tent talk" among the PNMs durng rush - both good and bad - "XYZ's skit was so lame" or "I met the most awesome girls at ABC".
And fraternity rush was at the same time as sorority rush. Since sororities couldn't feed PNMs more than snacks, PNMs would go to fraternity houses for meals (they used to say that if you had to pay for any meals during rush, you were doing something wrong
) and of course, over meals, they would hear things from brothers.