Rusty trombone is a euphemism for a sexual act in which a man stans with his knees and back slightly bent, with feet at least shoulder width apart in order to expose the anus. The other partner typically is on his or her knees behind the man and performs analingus while reaching up beneath the testicles or around the body to masturbate the man, mimicking the motions of a trombone player. The act is defined primarily by the physical orientation of the partners and the combination of analingus with manual penile stimulation; however, other positions and variations are possible.