Hello, William. Your alternatives are correct. I could add: "derriere" (comes from the French, meaning "butt"), pronounced "dairy air" "can", another euphemism for butt. "He kicked me in the can." "Butt" is actually short for "buttocks", so you could use that too. If you want to get anatomical, the butt muscles are, individually, called "gluteus maximus", so we say "glutes". Two points I would like to add: 1) "Kicking somebody's behind" and "kicking somebody from behind" are very different things. The first means what you are trying to say. The second means that you kicked somebody (anywhere on their body) while their back was turned to you (you were behind them). 2) The term "native American" means something different in the United States than "a person born in America". In the USA, it means a person of aboriginal descent, i.e. the original peoples (settlers) of the land now known as the United States. You should probably just stick with "How does an American explain this?".

Hi William. As a father, I use the word 'butt' often with my son and sometimes 'rear-end'. It's also common to hear 'behind' used as a noun here in the southern US where the first syllable is stressed, so it sounds like "bee-hind". "The donkey kicked the other donkey's behind."

Here in the UK people may use the word 'backside'. Americans may yes the word 'butt'.

In this case, use the preposition 'in'. "The donkey kicked the other donkey in the butt."