I can open my own present, look.

11 adults, average height around six foot, one room, estimate 20ft X 12ft, two sofas. Two octogenarians, both of whom had had (different) eye surgeries in the last week, one of whom is deaf (and won't wear their hearing aids), five under 25 yos and four "on the right side of 60" as my surgeon said to me first thing. Plus a dog.

Approximately 403 simultaneous conversations, none of them finished, on everything from supermarket self checkouts to published scientific papers (nephews g/f is quite clever really) to cars to running to how RFID works in shops to German Vs Russian in the difficulty stakes (nephew is fluent in both, also quite clever).

Hostilities were suspended for the day and  in the end it was a fun time. 

The pre party surgery went well too, with the advice that "it won't be the end of the world if you run on it but I'd leave it a few days". He put good stitches in.