I say things in a British accent even though I'm Canadian.
Why speak in a British accent then?
It is fun to pretend to be someone else.
It is essentially lying if you pretend to have an accent.  However, if you are just doing it for fun, it isn't that bad.
This is fine. Maybe I will pretend to be a US citizen next time.
You should just make it clear that you are joking to people about your accent, or you should make someone upset.