Pretend Murray
When you use a surname that you know isn't yours. You are given the name via a fake birth certificate to hide history, and the fact your "dad" isn't "your dad", but you go along with it to stay in good with your "chequebook dad"
Muzza is such a Pretend Murray he had it tattoo'd down his leg, and gave the name to his son who is now also a Pretend Murray. Spoon fed family lies are awful tastier than the truth huh?