I don't know if this really counts, but I hate it when I'm in public transport(train,metro, tram, bus whatever) and I run into someone I haven't seen for a long time you start chatting and before you know his/hers stop or yours is up and you'll have to leave each other without actually finding out how they were really doing. You'll tell each other to call, but you never do that...
It's too bad why do you always meet someone you haven't seen in ages when you're in a hurry and never when you are relaxing in a pub for example?