It's usually used satirically. It's a popular saying in China that has come to symbolize corruption. Specifically, the arrogant notion of some children of the privileged class that their parents' clout shields them from suffering the consequences of their misconduct
Grocery Store Owner: "Hey kid! Pay for that candy bar, or else I'll call the cops!"

Kid (running away with candy bar): "Screw you! 我爸是李刚 "My dad is Li Gang!"
by nothingburger April 24, 2011
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