Slumber party sounds like fun, but is it not another way of saying that slaves are like children? This slave is well past her slumber party days ooc (actually I don't think I was ever a slumber party type).
The books are rife with quotes that slaves were fully adult intelligent women, many of keen intelligence, grace and beauty. For an ooc event, it may be that a discussion day for open ooc exchanges between kajira, away from the Free might be helpful, especially to girls new to the role and/or new to Laura.
I think that there might be an IC way in RP of doing a "slumber party". I have heard stories of all the slaves being locked up centrally for their protection during threatening times and those events turning into actually great fun for the slaves who usually have little leisure or opportunity to swap wisdom, jokes and lore.