Some people believe that the phrase to 'Act Naturally' is an oxymoron, they think that 'Acting' means pretending and being 'natural' is the opposite of this.

This comes from old fashioned and misunderstood nature of what it means to Act. To act simple means to take action, somewher along the way, the meaning became something to do with actors pretending to be other people, but essentially the key to acting is to do less pretending and more being, the key to which is action (the meaning of the word Drama in ancient Greek)