Rusty trombone is the common name for a sexual act which simultaneously incorporates analingus and manual sex. It gets its name because one partner appears to use the other's body as a trombone, putting their mouth to the anus while stimulating the penis with one hand.
The first noted public use of the term was in 2003, when Detroit radio duo Deminski & Doyle used the term during a discussion of urban legend sex acts. It gained popularity in 2005 when it featured in a range of films including The Aristocrats, The 40-Year-Old Virgin, and Tenacious D in the Pick of Destiny.
A rusty trombone is also known as a dirty trombone, or sometimes shortened to rusty trom.
