American born-and-raised AFL star Mason Cox says he is unsure how to feel after being called a 'seppo' - sparking a debate about whether the term is friendly banter or a bigoted slur.

The towering Collingwood forward, who was recruited from playing US college basketball with Oklahoma State, went public with his experiences, as reported by the Herald Sun.

'Today I was called a ‘seppo’. I didn’t quite understand it but assumed it was meant to be derogatory,' Cox tweeted to his followers.

'Googled it and now not sure if I should be proud to be called a seppo?'

'Seppo' is a shortened form of 'septic tank' which is rhyming slang for Yank, and could be considered a putdown but can also be used in an affectionate way - much the same as Australians will use 'Pom' as a term for British people.

Some who responded to the tweet were of the opinion that it was a putdown.

'Don’t wear it. It’s derogatory. Not in common use, just used by racists/bigots who feel threatened,' one responded.

However the man known as the 'American Pie' felt the Magpies forward should not be offended.

'Embrace it , it's a term of endearement. Australian rhyming slang is fun when you get your head around it,' one responded.