a person who criticizes, objects to, or opposes something. One that takes the fun out of life. Synonyms: naysayer, cynic, complainer, defeatist, downer, killjoy, misanthrope, sourpuss, party pooper, curmudgeon, crank, kvetch, Debbie downer.
A vehicle traveling ten mph slower than the speed limit in the left lane of the freeway (a.k.a the fast lane) gabbing or texting on their cell phone with a line of vehicle behind them.
Driver: I HATE THIS IDIOT IN FRONT OF ME. I can't get by and I see them on their cell. I WANT TO RUN THEM OVER.