Dally sat right behind Cherry and Marcia and said inappropriate things; the book does not reveal what Dally was to have said, but states that he could "talke awful dirty" (pg. 20 in my version).
Dally was behind the two soc girls and called them rude and inappropriate names. Of course, in the book it is left hidden because this book was meant for school audiences as well.
I remeber Dally calling them bad things but it wasn’t listed in the book because it was school friendly. I do remembee in the movie Dally called the girl words lik the ‘B’ and ‘S’ word.