Submarine : noun Un submarine is a ship capable of navigating underwater, while diving.
Glass of white alcohol drunk before half a beer.
Submarine tip: technique used by some bar or restaurant servers which consists, by giving change to the customer, to put the big banknote under the smaller ones, so that the (drunk) customer forgets it.
You can also put the smallest banknote hidden under the receipt or the invoice; the currency being placed above.