the practice of preventing a driver from safely merging onto a freeway or other high-speed roadway. this is accomplished by the blocking car driving at the same speed as the merging car, and directly slongside. this action usually causes the merging driver to back off and merge behind the blocker; sometimes, though, the two cars collide because neither one gives way. often associated with NASCAR fans on public roads, on-ramp blocking is also common in major metropolitan areas.
jed: man, i couldn't believe it!! i was trying to get on the freeway, but some clown in a hyundai accent decided to ride alongside of me until we almost crashed at the entrance. what a jag-off!
ned: yeah, too many people commit random acts of on-ramp blocking these days. i'll take the back roads and avoid trouble.