Most offices are a hive of faction and splinter groups and there are always cliques. In fact the average workplace is quite complex in terms of its social interactions both away from and under the guidance of management.
For a brand new person who barely knows their own way to their office desk yet, it is quite an overwhelming situation which will take some time to integrate into.
If you have been working with the company for longer than the age of their office furniture then no doubt by now you will know all the in-jokes and probably take for granted some of the taboo comments and jokes commonly shared amongst co-workers. Each department may differ too; some may be laid back and joke with each other whilst other departments are deathly silent.
Within a couple of weeks any new person who had been added to the mix of complex human dynamics will begin to settle in and understand the work jokes and how factions communicate with each other. A new person will only feel settled when they understand the atmosphere of the office and the mentality and personalities of the people who are around them at work.