Origin of the term 
The term derives from hat trick, and since four is bigger than three, the rationale was that a four-strikeout performance should be referred to by a bigger hat, such as a sombrero. The "Olympic Rings" or platinum sombrero (which is now immortalized by a 5K race) applies to a player striking out five times in a game, while a horn (after Sam Horn of the Baltimore Orioles, who accomplished the feat in an extra-inning game in 1991) or titanium sombrero is bestowed upon a player who strikes out six times in a single game.
To date, only B.J. Upton has ever struck out more than five times in a nine-inning game. Striking out five times in a game has been achieved 63 times, most recently achieved by Starling Marte of the Pittsburgh Pirates on April 18, 2013.
On August 4, 2009, Tampa Bay Rays third baseman Evan Longoria went 2 for 6, recording a golden sombrero and 2 home runs. The second home run was a walk off home run. This feat was reproduced by Brandon Moss of the Oakland Athletics on April 30, 2013 in a 19-inning game against the Los Angeles Angels. They are the only players to record four strikeouts and two home runs (the second a walk-off) in a single game in the live-ball era.
On May 6, 2012, Baltimore Orioles third baseman Chris Davis had zero hits in eight at-bats as the designated hitter in 17 innings. His five strikeouts awarded him the rare platinum sombrero. In a bizarre twist, he also recorded the win in that game when called in to pitch two innings of relief, making him the first positional player from the AL to record a win since 1968.
On June 16, 2012, the Washington Nationals hosted the New York Yankees in interleague play. In the second game of the series, Nationals rookie Bryce Harper had seven at-bats over fourteen innings, striking out five times to record a platinum sombrero. He was also the final out of the game, as, with two outs in the fourteenth, he grounded out with men on first and second to end the game.
On May 6th, 2013, B.J. Upton struck out four times in his first four at bats, recording a golden sombrero by the end of the 6th inning.
The record for strikeouts in a game in all of professional baseball belongs to Russ Laribee of the minor league Pawtucket Red Sox, who in 1981 struck out seven times in a thirty-three inning baseball game.
Major league players with six strikeouts in a game 
|Carl Weilman||July 25, 1913||15||St. Louis Browns|
|Don Hoak||May 2, 1956||17||Chicago Cubs|||
|Rick Reichardt||May 31, 1966||17||California Angels|||
|Billy Cowan||July 9, 1971||20||California Angels|||
|Cecil Cooper||June 14, 1974||15||Boston Red Sox|||
|Sam Horn||July 17, 1991||15||Baltimore Orioles|||
|Alex Gonzalez||September 9, 1998||13||Toronto Blue Jays|||
|Geoff Jenkins||June 8, 2004||17||Milwaukee Brewers|||
- "Baseball Reference - "Golden Sombrero"".
- Michael, Matt (April 9, 2005). "Extra bases". Syracuse Post-Standard.
- ESPN - More amazing stories to watch for - MLB
- Jayson Stark, ESPN.com
- Peter Gobis, in the Sun Chronicle
|Look up golden sombrero in Wiktionary, the free dictionary.|
- Baseball Tips.com: Baseball slang
- Rocky Mountain News August 17, 2006 quoting Don Baylor
- Athlon Sports May 8, 2007: 4 leadoff hitters with golden sombrero.
- List of strikeout records at Baseball Almanac
- Baseball Reference - Most natural golden sombreros