Cock Block:
The action of preventing a male from scoring on a
female.
Example:
Hypothetically, at a bar mitzvah, a
boy named Ryan and his SO, Harley, are making out. Harley'
s friend Remy was driving her
home. While they were hooking up, Remy lies about them having to leave. This is preventing Ryan from going further, thus a cockblock. In this situation, Remy is a cock blocker, and the action where she cock blocked, was tricking Harley to stop.