Cape Town ? There is a very good reason why you have never heard anyone call Matthew McConaughey ?Matt?. The 47-year-old stopped by Jimmy Kimmel Live! He explained, ?Halfway to the monkey bars I feel this hand on my shoulder and I look and it?s my mother and she?s like ?What are you doing?? and I said ?I?m going to play on the monkey bars with John?. ?And she goes ?Who is??