What's a CB? It's a cock-blocker. This term refers to anyone who stands between you and the best cock in town. A typical cock-blocker is another woman (or man) in the room who's after your man. But it doesn't mean you're necessarily competing for the same thing. Mamas are expert cock-blockers--they don't want you stealing their sons. You can even be cock-blocked by your own children, if they're jealous of any man treating their mother like a woman instead of as a person who gave them life. You must always be aware of potential cock-blockers and be prepared to confront them in any way necessary. When a dog is eating, smart people refrain from attempting to get between that dog and the bowl. Be that dog.
Janice Dickinson in her book Check, Please: How To Pick Up Boys...& Dump Them When You're Done.