A Puerto Rican Roadblock is when you are on a 4-lane highway, and you move beside another car and match it's speed. This is normally done to piss someone off who is trying to get around you.
Bob: There's a guy in a sports car is coming up really fast.

Rob: Pull up to that other truck and do a Puerto Rican Roadblock

Bob: Haha, yea. Lets keep him behind us until we hit our exit in 50 miles
by THE Mr. Waffle January 27, 2010
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When 2 or more vehicles (normally trucks) lineup side by side on a highway and slow down traffic behind them while also making themselves unpassable.
Look at those 2 f******' semi's up there. We're goin' nowhere it's a Puerto Rican Roadblock!
by WHAT'S YOUR PRICE FOR FLIGHT December 26, 2011
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