Five members of a jury "friend" each other during a jury trial. In another trial, one involving murder, jury members look up key scientific terms on Wikipedia during deliberations. The jury looked up terms helping them understand how blood settles, an important issue in the murder trial. Court personnel found the results of the research after the trial was complete. Of course, a jury is supposed to only consider the facts and information presented during trial. They are not supposed to do their own research. Both instances occurred in Maryland. That state is now considering adding jury instructions to specifically prohibit online research by jury members.
In the Facebook incident, five jury members formed a clique, allegedly upsetting the jury dynamics. That is a problem since most jury instructions tell the jury they cannot discuss the case until both sides have rested and concluded their presentation of evidence. One of the five apparently heard suggestions on how the trial should turn out from an outside observer. One of the parties to the trial is seeking a new trial. So, yes, forming a clique too early would be a problem. See ABA Bar Journal for more info.