10 mph.
Re time share reps. Listen to them for 15 seconds. Tell them nicely that you are not interested. Listen for another 15 (they don't particularly stop when you are not interested). Then, in a loud voice, say, "I DON'T WANT TO BUY YOUR DAMN DRUGS, AND I SURE AS HELL DON'T WANT YOUR 10 YEAR OLD SISTER. WHAT KIND OF LOW-LIFE SELLS DRUGS AND PIMPS HIS LITTLE SISTER?". If there are other people around, it will work fine and he'll leave you alone. If there are no other people around, he may beat the crap out of you.