"5 shots" joke

One day a guy walks in a bar and asks for five shots of whiskey.
The bartender asks why.
The guy says, "I found out my brother is gay."
The same guy, comes in the next day and asks for ten shots of whiskey.
The bartender asks why.
The guys says, "I found out my other brother is gay."
The next day, the same guy comes in and asks for fifteen shots of whiskey.
The bartender asks why.
The guy says, "I found out my other brother is gay."
The bartender says, "Doesn't anyone like pussy anymore?"
The guy says, "Yeah, my sister."