What is In For A Penny, In For A Pound!?
1.
"If you're going to take a risk at all, you might as well make it a big risk."
From an old British expression (thus "pound" instead of "dollar"); the original reference was probably to theft (though this is not certain), saying that being arrested ("taken in") for stealing a small amount is just as bad as for a large amount, so you may as well steal a lot and hope to get away with it.
An equivalent expression is, "As well hanged for a sheep as a lamb", where it's implied that you are stealing the animal. If the punishment for failure is the same, you may as well try for the largest possible reward.
The phrase is often misused with reference to a punishment that is out of proportion to a crime, but this is not the actual meaning.
"I could get fired just for talking to you. Well... in for a penny, in for a pound! Come on in."
See
2.
An expression of 70's street culture that means that if you participate even slightly in something, you are fully involved in the consequences.
Frank: "Charlie got 5 years for that liquor store hold-up, and he was just the look-out!"
Sam: "Well, you know what they say, 'in for a penny, in for a pound!'"