Autistic people can have difficulty with communication. They can take things literally such as phrases like ‘pull your socks up’ which to those of us without autism usually means hurry up. To a person with autism means physically pulling up your socks. This can lead to confusion for people with autism especially if they aren’t wearing socks at that particular time! This is also true of sarcasm so be clear and say what you mean and mean what you say. People can also have difficulty getting their own point of view or opinion across as they may not be able to find the words they need.  A lot of autistic people also have a processing difficulty that means they need a bit longer to process what has been said to them and then to formulate the reply they wish to give. Reading body language and facial expressions can also be difficult for someone with autism.  What does a smile mean?   This can mean misunderstandings which can lead to inappropriate behaviour.