A few times i'll have gotten a number on a night out, and then when i text them in a day or two, they ask for my last name?

Obvious they want to see what they can find out about me, but i've played elusive in the past, holding frame and agree and amplifying, not giving them an honest answer. They never like it.

It annoys me because almost every group of female best friends i've spoken to do this. I can bet with a 90% certainty that she wants my last name so she can facebook me, show me to her friend(s), make judgements about me and shit like that.

Some have gotten really pissed off before, and I had one girl ringing me from 3 seperate numbers, going from pleasing for my last name to getting really angry and saying I pissed her off. I held frame at all times.

How to deal with this?

EDIT: Grammar and question at the end.