Why Is 'Act Naturally' Not Necessarily An Oxymoron?

An oxymoron is a phrase involving words that should not easily sit together. This is where two or more of the words seemingly contradict each other.  Some amusing ones are 'Military Intelligence' or 'Microsoft Works'.  Some examples from Shakespeare:  'parting is such SWEET SORROW', sorrow is not normal considered sweet.  'Oh Brawling Love'.   This is of course unusual because Love is not usually considered to be fighting or brawling.  Shakespeare uses this tool of rhetoric to show contrasting feelings in his characters.

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).