If a British person is a Brit...

Is a Japanese a Jap? (of course; but it might’ve been offensive, sorry)
A Canadian a Can?
An Italians an It?
A German a Germ?
And an American an AIMer? (changed spelling a little..; also, alliteration!; it’s also kind of true)

Slowly adding… sorry if any offend you.

Not-funny:
A Turkish person a Turk? (True, isn’t really funny)
A Polish person a Pole? (that’s true, actually)
A Spanish person a Span? (of a bridge… get it?)