I used to just sit quietly in the corner nursing my non-alcoholic drink or cup of tea and hoping nobody spoke to me. But of course this would lead to me "thinking too much" and getting in a state because I couldn't enjoy it like everybody else did. So my latest tactic, apart from NOT GOING, is to take on a job to keep me occupied and out of trouble ... food prep, clearing up, washing up, errand runner, whatever ... I often get a little over-zealous with this though and people think it's a bit weird, but I'm much more comfortable DOING something than sitting uncomfortably in a corner. When I do have to sit, I try not to put earphones in because that obviously comes across as "being rude", but I do play almost constantly with my iphone (I have a few games for this purpose that keep me calm - people generally just think I'm a text-a-holic, but that is not true).