Coming home from work one day, my boyfriend and I found ourselves sat on the front two seats, facing the line of fold-down sideways-facing seats, which were unoccupied. As we reached Osborne, a girl got on, sat on the sideways seat and said loudly "WHY ARE YOU SO MEAN TO ME?", while staring in our direction, towards everyone else on the bus. It took us (and the whole bus) a while to realize that she was wearing a cellphone headpiece and was arguing with some poor soul on the other end. The silence that came after her demand, along with the strange stare down the bus and the fact that the cellphone cord was hidden by her hair, put everyone on edge!
So, listen up crazies:
1) Those headphone things are meant for when you can't use your hands - if you're sat on the bus, just hold your phone to your ear! At least then it's obvious you're not picking a fight with a stranger (or maybe your are, we don't know who's on the other end. Bottom line: if it's not aimed at us, we don't care)
2) If you're going to talk into seemingly mid-air, don't stare at other people while you do it, it's just WEIRD.
I've also seen courteous people hold the mouthpiece part of their phone closer to their mouth, so a) they can speak quietly, and b) give everyone else the signal that they're not just talking to themselves.