The Nassau is a type of wager in golf that is essentially three separate bets.
The Nassau bet gets its name from the Nassau Country Club on Long Island, where the format is said to have been invented in the early 1900s by club captain John B. Coles Tappan.
In fact, the other clubs would not play Nassau CC because they were tired of losing everything.
The Nassau press is a side bet, in addition to the original bet, offered during a Nassau match by the side that is losing in an effort to even their money for either the front nine, back nine or overall.
This is basically a double-or-nothing proposition for the player in the lead.