Drinking Code

A blonde, a brunette and a redhead walked into a bar.
The brunette said to the bartender "I'll have a B and C."
"What's a B and C?" asked the bartender.
"Bourbon and Coke," replied the brunette.
"I'll have a G and T," said the red head.
"What's a G and T?" asked the bartender.
"Gin and tonic." replied the red head.
"I'll have a15," said the blonde.
"What's a 15?" asked the bartender.
The blonde rolled her eyes and said,"Duh, a 7 and 7."