Simplify the following text for a Grade 9 native English-speaking person.
Original: Ass to mouth is a common colloquial term used for the removal of the penis from the passive partner 's anus followed by the immediate insertion of the penis into the passive partner 's or another partner 's mouth .
Simplified: Ass to mouth is a common term that describes one partner removing his penis from the anus , and inserting it into his partner 's or another person 's mouth .