Why not jacket instead of coat we tranalate frakke as jacket in other sentences.
''you are wearing your potato''
Why is "på" in de sentence?
"Du her din frakke" would mean "You have your coat", the på indicates that "du" are wearing the "frakke" (exactly like the English: "You have your coat on")
I decided you can translate 'på' to 'on'. So 'you have your coat on' translates just fine.
I translated it back to Dutch "je hebt je jas aan" instead of the less common "je draagt je jas" and it suddenly made a whole lot of sense
Why is cloak wrong?
A cloak is not a coat. A cloak is an overgarment, normally sleeveless. You will never see a cloak nowadays, except perhaps on fine ladies going to an opera. Please see this link: https://en.wikipedia.org/wiki/Cloak
It is embarrassing enough when you don't realize that your glasses are on your head. But your coat, whoa!