Question:
Chong was born at the University of Alberta Hospital in Edmonton, Alberta, on May 24, 1938, and given the name Thomas B. Kin Chong at birth. His mother was Lorna Jean (nee Gilchrist), a waitress of Scots-Irish ancestry, and his father was Stanley Chong, a Chinese truck driver who emigrated to Canada from China in the 1920s. The senior Chong had first lived with an aunt in Vancouver after arriving in Canada. As a youth, Tommy Chong moved with his family to Calgary, settling in a conservative neighbourhood Chong has referred to as "Dog Patch".
In 2003 Chong became caught up in two American investigations, code-named Operation Pipe Dreams and Operation Headhunter, which tried to trace drug traffic and users through businesses selling drug paraphernalia, mostly bongs. Operation Pipe Dream was run from Pittsburgh. US Attorney for Western Pennsylvania Mary Beth Buchanan oversaw the case. The estimated cost of Operation Pipe Dream was over $12 million and included the resources of 2,000 law enforcement officers. Fifty-five companies that sold drug paraphernalia over the Internet were the subject of the investigation, and Nice Dreams was one of them.  Chong was charged for his part in financing and promoting Chong Glass/Nice Dreams, a company started by his son Paris. His case never went to trial, as his attorney negotiated a plea agreement with the US Attorney for the Western District of Pennsylvania's Office. He admitted to distributing 7,500 bongs and water pipes on the Internet through Nice Dreams, a family company. Chong agreed to plead guilty to one count of conspiracy to distribute drug paraphernalia in exchange for non-prosecution of his wife, Shelby, and his son, Paris. Chong cooperated with the government and was the first of the Operation Pipe Dreams defendants to plead guilty.  At Chong's sentencing, Assistant U.S. Attorney for Western Pennsylvania Mary McKeen Houghton said in her arguments that Tommy Chong "used his public image to promote this crime" and marketed his products to children. U.S. Attorney Mary Beth Buchanan also was present at the sentencing in Pittsburgh and released a statement to the press stating, "there are consequences for violating the law, even if the violator is a well-known entertainer like Thomas Chong."  While Chong argued for community service and home detention at his sentencing, the district judge, Arthur J. Schwab, denied his requests and sentenced him to 9 months in federal prison, a fine of $20,000, forfeiture of $103,514, and the loss of all merchandise seized during the raid of his business. Chong served his sentence at the Taft Correctional Institution from October 8, 2003 to July 7, 2004. He was a cellmate--or "cubie"--with "The Wolf of Wall Street" Jordan Belfort, and is given credit for encouraging Belfort to write his memoirs. They have remained friends ever since.  These events were among those chronicled in a/k/a Tommy Chong (2006), a documentary by Josh Gilbert. It premiered theatrically at the New York Film Forum in New York City and won awards. His time in prison was also a main point in his book, "The I Chong".
Answer this question using a quote from the text above:

what does US vs Chong refer to?

Answer:
Chong became caught up in two American investigations,

Answer the question at the end by quoting:

"Hound Dog" is a twelve-bar blues song written by Jerry Leiber and Mike Stoller. Recorded originally by Willie Mae "Big Mama" Thornton on August 13, 1952, in Los Angeles and released by Peacock Records in late February 1953, "Hound Dog" was Thornton's only hit record, selling over 500,000 copies, spending 14 weeks in the R&B charts, including seven weeks at number one. Thornton's recording of "Hound Dog" is listed as one of the Rock and Roll Hall of Fame's "500 Songs That Shaped Rock and Roll", and was inducted into the Grammy Hall of Fame in February 2013. "Hound Dog" has been recorded more than 250 times. The best-known version is the July 1956 recording by Elvis Presley, which is ranked number 19 on Rolling Stone magazine's list of the 500 Greatest Songs of All Time; it is also one of the best-selling singles of all time.
Two records were released that were neither cover versions of nor answers to Thornton's release, yet used a similar melody without any attribution to Leiber and Stoller. The first was Smiley Lewis's "Play Girl", credited to D. Bartholomew and released by the Imperial Records label (Imperial 45-5234) by the end of March 1953. Described as a "stomping uptempo boogie rocker", it began: "You ain't nothin' but a Play Girl / Staying out all night long". In April 1955, female impersonator Jesse "Big 'Tiny'" Kennedy recorded "Country Boy" accompanied by His Orchestra that was released by RCA's Groove Records (Groove 4G-0106) by May 21. While credited solely to Kennedy, this song has a similar melody to "Hound Dog": "'Country Boy' has a deceptively slouching flip on the 'Hound Dog' motif - this time with Tiny proclaiming proudly that he 'ain't nothing but a country boy'".  In the early 1970s Robert Loers, owner of Dutch label Redita Records, found a song with the same melody as "Hound Dog" called "(You Ain't Nuttin' But a) Juicehead" on an anonymous acetate at Select-o-Hits, the Memphis distributorship owned by Sam Phillips' brother, Tom, where Sun artifacts were stored.  When Juice Head first appeared on a Redita Records LP [in 1974], it was credited to Rosco Gordon. But it's not Rosco. It simply is not him. Really. Even Rosco confirmed that. It might not even be a Memphis Recording Service demo. Just substitute the words "Hound Dog" for "Juice Head" and what have you got? Of course the inspiration for this song came from Big Mama Thornton's "Hound Dog" or perhaps even from Rufus Thomas' "Bear Cat". But the song's other parent is Eddie Vinson's slowed down "Juicehead Blues" which harks to the previous decade...If indeed this originated from Sam Phillips' studio, it was nothing that Phillips needed to touch because it was another lawsuit waiting to happen."  Philip H. Ennis sees "Two Hound Dogs", which was recorded on May 10, 1955, by Bill Haley & His Comets (Decca 29552), as a response to Thornton's recording. While not an answer record in the traditional sense, the lyric characterized "Rhythm" and "Blues" as the titular "Two Hound Dogs," an apparent testament to the stature of "Hound Dog."

Who did the last riff
You Ain't Nuttin' But a) Juicehead" on an anonymous acetate at Select-o-Hits, the Memphis distributorship owned by Sam Phillips' brother,