I sit there and shout out slogans of 'encouragement.'
Actually, I diverted a friend from fighting. A guy we knew (but didn't know it until we approached him) had a bat in his hand that he was going to 'use,' I guess. Well, he knew me and I've always been people's 'friend' (I should say 'friendly' as I always know how to divert people from wanting to beat me up to seeing me as too 'friendly' to attack - call it a skill I was never aware of). Anyways, myself and this guys 'girlfriend' were in the middle of it. My friend is a big guy, 6'2" and about 230 lbs and would have probably crushed this guy who was shorter then me (I'm 6ft) and I KNOW not very strong. This girl and I were humouring each other more then these 2 guys but eventually, we won.
If I dont know the people I do what everyone else does - nothing. The more people around the less inclined you feel to stand up and help.
Another friend was screaming at a kid on the way home after a crumby new years party. I was going to let him get his ass kicked for trying to start something.. Never saw that kid again - I think he, himself, was aspie