Myuncleyeah, is more of a pharse used by men of Indian or pakistani origin to explain that there Uncle(male family member or elder), has told them some information (usually mis-information) and they are relaying it to a third party.
"Myuncleyeah says that your doing tyres for £20 each yeah"
Abdul "Myuncleyeah said your open til 6 yeah?? I know its 5 to 6 but i need my tracking doin innit, i'll be 10 minutes yeah??
Receptionist "Fuck off you cheeky cunt"