From the Post:

The rookies' hazing didn't end when the Yankees arrived at the team hotel Monday night. Jason Giambi invited the rookies who were dressed in Wizard of Oz garb for the flight from New York to the Capitol Grille in Tampa for dinner. The only requirement was they stayed in their costumes. ...

The night out cost Giambi roughly $5,000 and was appreciated by the guests.

There are quotes from Giambi, Clippard and Kennedy in the article.