Hrm... Depends. My best friend can be a real idiot sometimes... But he can run faster than me, so I don't think I would even be able to. If I could, I'd probably help him.
Um... I wouldn't trip hyim, but if the zombie horde consisted of over 10+ zombies I would try and get away as fast as I can along with my friend. There would be no point in fighting because both of us would get annihilated
No, I'd go kick some zombie ass with 'em. We talk about this thing all the freakin' time. You need more information in order for this to actually be entertaining or useful.