How old are you?
If you are:
under 12, ignore what he said and go read your books..
13-17, tell your friend politely, "thats illegal, u dunno
sh*t"..
18-21, you should know what that doggy has a more profound
meaning that "walking the dog"..
22 and above, by now, you should already know the real meaning
of doggy.
Seriously.. How old are you?