Stan's Bolo Tie.
Stan's Bolo Tie was a bolo tie given to Stan by his grandfather in the Season Sixteen episode, "Cash For Gold".
Background
Some time before "Cash For Gold", Marvin Marsh bought a gold, diamond-and-turquoise-studded bolo tie as a gift for his grandson. At the start of the episode, he gives it to Stan, who is guilted into wearing it. After Kyle recommends they sell it to a Cash For Gold, they unsuccessfully attempt to sell it to three different stores. Near the end of the episode, Marvin, seemingly have forgotten he was the one who bought it for Stan, tells him that the tie "is fucking gay as fuck". Stan responds, saying that he will no longer wear it; Marvin states that that is a good idea.
Appearance
The tie is fourteen carat gold. Several small diamonds form a circle around its center, which contains a large turquoise gem.