If someone asks for your number, and you don't want them to have it, don't get all flustered and embarassed trying to a)save face and b) remember someone's number that you hate. Just give them the number to the rejection hotline. A seemingly reasonable phone number will tell the caller this:
"Hello, this is not the person you were trying to reach. This is (insert city name here) Denver's rejection hotline, because the person that gave you this number did not want you to have their real number."
The message goes on to insult the caller profusely, finally saying that "possibly going out with you is as attractive as playing leap frog with unicorns"

I have memorized Denver's rejection hotline number.