Well, that's one of the benefit of a Democracy, is you can make fun of or chum around with the Commander in Chief, and not get beheaded for it. Nothing expresses the colorful character of United States culture like the nicknames we give our Presidents. Here are some of the best, with the stories behind them.
Shrub (George Walker Bush) - A name bestowed in the writings of the late Molly Ivins, the American columnist and author. Seen by many as the Dorothy Parker of modern politics, it took a sharp wit like Molly's to draw the connection between the surname "Bush" and a reference to the Junior President being hardly capable of filling the shadow of Bush Senior.
Slick Willie (William Jefferson Clinton) - Bestowed by an editorial article in the "Arkansas Democrat Gazette", this nickname does the skillful job of referring to the "Teflon" nature of Clinton where nothing ever seemed to stick to him, his charismatic skills, a reference to his way with the ladies, and a kind of 1940's-era risibility, all without condemning him too hard.
The Gipper (Ronald Wilson Reagan) - Named after an actual role he played in the movie "Knute Rockne, All American". The movie was about football and Ronald Reagan played George Gipp. The lead character actually had the line: "The last thing George said to me, 'Rock,' he said, 'sometime when the team is up against it and the breaks are beating the boys, tell them to go out there with all they've got and win just one for the Gipper." Reagan actually cheerfully adopted this nickname himself.
The Accidental President (Gerald Ford) - Ford had a reputation for being physically clumsy and his many slips and falls were caught on camera. Most famously was when he tripped coming out of his jet, Air Force One, and tumbled down about 12 feet of steps. Combined with this, he had never run for President or Vice President, since Nixon appointed him from Congress directly to the Vice Presidency to replace Spiro Agnew. Nixon then was ironically impeached himself, leaving the tiller of the nation in Ford's shaky hands.
Tricky Dick (Richard Milhous Nixon) - No list of colorful Presidential nicknames would be complete without it. First coined by Democratic opponent Helen Gahagan Douglas, during the 1950 race for the California U.S. Senate. The name was applied for Nixon's already questionable tactics when competing for a Senate seat, and even then compared to his later record the public had seen nothing yet.
Give 'Em Hell Harry (Harry S. Truman) - This was shouted out from a crowd listening to one of his famously fiery speeches, and the name stuck throughout his Presidency as he earned the reputation of a vigilant watchdog of the nation's well-being.
The Sphinx of the Potomac (Calvin Coolidge) - The president was known for being the most taciturn official ever, and legends abound of how difficult it was to get him to talk. This made him enigmatic; nobody knew what he was thinking, and so he was silent and mysterious like an Egyptian sphinx.
The Professor (Woodrow Wilson) - Surprisingly enough, an academic with his own thoughts and no need for speech-writers is the exception in the Presidency rather than the norm. But Wilson was one of these, and was one of the few to be hailed as an intellectual. Compare this with later Presidencies where jokes at the expense of the President's I.Q. are the norm.
The Lion (Theodore Roosevelt) - It is difficult to pick from the many colorful nicknames given to Roosevelt the first, however, this one sums up his military record before his time in office, and his grit and determination in rooting out corruption on his way to the top. He ruled with a very firm hand, and this nickname speaks of that character in an almost Biblical state of reverence.
His Obstinacy (Grover Cleveland) - A President famous for his use of the veto power; he had a rubber stamp and he wasn't the least bit afraid to use it. Cleveland himself later bragged that his greatest accomplishment as President was blocking the bad ideas of others.