A)When talking about a girl with large boobs they are refered to as doubble big macs to limit akwardness. It can also be used to hide what you are saying if they are within hearing distance.
B)A greasy but delitious burger sold ad Mcdonalds.
Ex.1: Damn, That girls got doubble big macs
Ex.2: Man would realy like a girl with doubble big macs
Ex.3: I'm hungry, can we go to Mcdonalds and get some doubble big macs mommy?