Men, Don't Talk To Your Sisters-In-Law, Haredi Modesty Sign Says
Hilchos tznius (the laws of modesty) between men and women are also required to be observed by brother-in-laws, sister-in-laws and cousins.
• Unimportant talking, shmoozing and laughter is not allowed.
• It is forbidden to play games together; this is an inappropriate activity.
• Gender segregation between men and women relatives must always be fully in place.
[Hat Tip: Burich.]