Two co-workers who are friends:
1- She is very, very nice, but she doesn't take "end the conversation" cues well, so she just keeps talking and talking and you can't pull out of the convo without possibly hurting her feelings. I usually escape by making a joke and exiting on the laugh.
2- The other one is forever overanalyzing office politics and not in a very smart way, as in I think her analysis is usually incorrect. It makes me either want to block her IMs or beat her about the head with a blunt object.