Henry Winkler is in the Green

Now, when Henry Winkler wore this fine green sweater he could have been in Manchester, England, signing copies of his children's book Hank Zipzer Niagara Falls or Does It?

But, based on that cup, we're pretty sure he was at a frat party.

The color green and a booze reference?  Yup.  Totally gearing up for St. Patty's.