A play on the metric miles per gallon. Describes the overall fulfillment and enjoyment of a driving experience, rather than fuel economy. Used often in the car enthusiast community, when referencing vehicles that focus primarily on performance rather than daily drive-ability and convenience.
That car may suck up gas, but it makes up for it in smiles per gallon.
Being fake to someone. Acting like you're cool with someone then going and talking shit behind their back. Similar to crocodile tears but more of a "happy" fake.
Person 1: Hey brother! How's it going dude?
Person 2: I ain't your brother. Fuck you and your crocodile smiles.