The discussion about the slang term "gate" provides us with an opportunity to give well deserved "props" to Clarence "Gatemouth" Brown;

Here's an excerpt from his Wikipedia page:

Clarence "Gatemouth" Brown (April 18, 1924 — September 10, 2005[1]) was a Louisiana and Texan American blues musician.

He was an acclaimed multi-instrumentalist, who played an array of musical instruments such as guitar, fiddle, mandolin, viola as well as harmonica and drums. He won a Grammy Award for Traditional Blues in 1983 for his album, Alright Again!

Born in Vinton, Louisiana, Brown was raised in Orange, Texas. His professional musical career began in 1945, playing drums in San Antonio, Texas. Tagged with the "Gatemouth" handle by a high school instructor who accused Brown of having a "voice like a gate," Brown has used it to his advantage throughout his illustrious career.[1] He took note, and his fame took off, during his impromptu fill-in in a 1947 concert by T-Bone Walker in Don Robey's Bronze Peacock Houston nightclub.[1] When Walker became ill, Brown took up his guitar and played "Gatemouth Boogie," to the delight of the audience."

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Gatemouth Brown's nickname is similar to that of the great jazz trumpeter & singer "Satchmo" Louie Armstrong . "Satchmo" is short for "Satchelmouth". See this quote from http://ask.yahoo.com/20021111.html

"Some say his nickname [Satchelmouth]* stemmed from his wide, infectious grin, while others state it was a nickname he earned in band class as his cheeks blew up when he played the cornet.

Regardless, "Satchmo" was coined during a 1932 trip to London when a magazine editor greeted Armstrong with "Hello, Satchmo." Armstrong liked the shortened version of his nickname so much he used it as an album title. It stuck."

* a "satchel" is a large bag with shoulder straps