What's your twenty?

This is one of many CB slang terms that those operating CB radio used mainly during the CB craze of the 1970s and 1980s.
Literaly speaking it means: Where are you?

What's your twenty?" This is asking the receiver what their current location is. This term comes from the ten-code 10-20.
For more info check Wikipedia.org and search for "CB slang"

by Neriglissar October 26, 2006