The opposite of a rusty trombone. Internationally hand signalled by pointing your index finger toward a fictional v-hole while feigning to lick an imaginary fecally stained sphincter.
The other night when my girl came over, instead of getting a rusty trombone I thought I'd do something nice for her. I told her to use the Kamode but not to wipe. Tonight was going to be her special night. The night of the rusty sewing machine.