Wiktionary
n. 1 (context golf chiefly British English) The clubhouse at a golf course. 2 (context golf humorous English) The pub after a game of golf. (rfv-sense: English)
Wikipedia
In golf, the nineteenth hole is a slang term for a pub, bar, or restaurant on or near the golf course, very often the clubhouse itself. A standard round of golf has only eighteen holes, so golfers will say they are at the 'nineteenth hole', meaning they are enjoying a drink after the game. The concept is similar to Après-ski in skiing.
The 19th hole on miniature golf courses is often a hole in which if a hole-in-one is scored, one receives a free game.
Usage examples of "nineteenth hole".
That meant Robbie couldn't meander through the round with Tuohey waiting for him to get conversational at the nineteenth hole.
When you're done you get to hang out at the nineteenth hole and drink beer and lie about your game.
So it was tantalizing later, in the Nineteenth Hole, to listen to Julio Pugaliese spin out a rambling story about a man who had a quarter of a million dollars' worth of stolen bonds and did not know what to do with them.
They sat, having a cold one after their round, near a large window in the Nineteenth Hole, overlooking the practice putting green.
Nowadays I am Howard the Conqueror, stock broker extraordinaire, terror of Derry Municipal Country Club, frequent habitue` of what is known at golf courses all over the world as the Nineteenth Hole, but in '71 I was part of a medical assistance team in the Mekong Delta, a scared kid who sometimes woke up wet-eyed from dreams of the family dog, and all at once I know this feel, this smell.
It would tire you to remember that DO meant b, TU o, and RO y, and that to say he-boy you must prefix the ape masculine gender sound BU before the entire word and the feminine gender sound MU before each of the lower-case letters which go to make up boy--it would tire you and it would bring me to the nineteenth hole several strokes under par.