Context

This line was spoken by Lloyd Bentsen in the 1988 Vice Presidential Debate.

Political debates were rowdy even before Joe Biden was making faces at people. In 1988, Republicans George Bush (the first one, who now skydives and gets painted by his son) and Dan Quayle ran against Democrats Michael Dukakis and Lloyd Bentsen.

At the Vice Presidential debates, those who didn't switch the channel were treated to one of the biggest verbal smackdowns ever televised outside of The Jerry Springer Show.

After Dan Quayle compared himself to "Jack Kennedy" (i.e., JFK), saying, "I have as much experience as Jack Kennedy did, when he sought the presidency," Lloyd Bentsen shut it down. "Senator, I served with Jack Kennedy. I knew Jack Kennedy. Jack Kennedy was a friend of mine. Senator, you're no Jack Kennedy."

Even though Bush/Quayle steamrolled over Dukakis/Bentsen in a landslide victory, Bentsen was right—Quayle is no Jack Kennedy. JFK knew how to spell potato. 

Where you've heard it

Not only is this one of Time magazine's most memorable debate moments ever, but Senator Bentsen's spiritual successor in sass, Joe Biden, referenced the quote during his 2012 debate with Republican VP candidate Paul Ryan. Ronald Reagan also gave his spin on the quote during his criticism of Bill Clinton. 

Pretentious Factor

If you were to drop this quote at a dinner party, would you get an in-unison "awww" or would everyone roll their eyes and never invite you back? Here it is, on a scale of 1-10.

Comparing yourself to JFK is a 10; calling someone out on it is totally okay.