Three Blondes At A Bar

A blonde walks into a bar and asks the bartender for a WW. Not knowing what that was, he asked the blonde what it was and she told him a White Wine. So he gave her some white wine.

Another blonde walks into the bar and asks the bartender for a RW. Again not knowing what it was, he asked the blonde. She told him it was a Red Wine. So he gave her some red wine.

Then a 3rd blonde walks into the bar, and asks the bartender for a Double7. Very confused, the bartender asks what that is. And the blonde says, "Duuuh! 15!".