Meereenese Knot

The Meereenese Knot is a difficult-to-perfom act of contortion or sexual gymnastics, originating in the city of Meereen on Slaver's Bay. Kayla, a prostitute in King's Landing, is one of the few women known to be able to peform it.

Season 3
Tyrion Lannister commissions several prostitutes, including Kayla, to help Podrick Payne lose his virginity. He commends Kayla on her ability to perform the Meereenese Knot.

In the books
In the Song of Ice and Fire novels, the "Meereenese Knot" is a reference to a complex series of plot problems George R.R. Martin encountered whilst writing the fifth novel in the series, A Dance with Dragons, problems which delayed the novel for a considerable amount of time.