Scotch with two drops of water

An old lady on a cruise orders a Scotch with two drops of water.
As the bartender gives her
the drink she says, "I'm on this cruise to celebrate my
80th birthday and it's today."

The bartender says "Well, since it's your birthday, I'll
buy you a drink. In fact, this one is on me." As the woman
finishes her drink, the woman to her
right says, "I would like to buy you a drink, too."

The old woman says, "Thank you. Bartender, I want a Scotch
with two drops of water." "Coming up," says the bartender.

As she finishes that drink, the man to her left says, I
would like to buy you one, too." The old woman says, "Thank
you. Bartender, I want another Scotch with two drops of
water." "Coming right up," the bartender says.

As he gives her the drink, he says, "Ma'am, I'm dying of
curiosity. Why the Scotch with only two drops of water?"
The old woman replies, "Sonny, when you're my age, you've
learned how to hold your liquor. Holding your
water, however, is a whole other issue."