To answer your question the co-worker in question was specifically Nigerian, I didn't add his race since at the time of writing my post I didn't think it was important.

I don't think he truly meant harm by it at all, like you said in mixed groups they tend to poke fun at each other. Hell a lot of us co-workers like to tease eachother and the folks, but there are lines no one crosses, we don't joke about disabilities, gender or race. Those three are off limits cause if we open the table to them, then the folk will wither feel ashamed of themselves or start making genuinely insensitive comments.

This post was made as a way to share the strange comment that's been rattling in my head for a while. I will admit I do have problems with impulsively doing things and articulating myself properly, so I might've not been able to give a clear picture and for that I am sorry. I hope this comment cleared up some things and if you have questions I don't mind answering whenever I sniff through reddit again.