An egg is a joking term for someone of Caucasian extraction who shows more interest in Asian culture (especially East Asian...Chinese, Japanese, Korean, etc...) than Western culture, or who "acts Asian." This may include interest in Asian languages, dress, history, habits etc. The term uses the food motif of the more common banana, which describes the inverse: a person of Asian heritage who is more interested in Western culture.

The metaphor has to do with racial colors: a banana is yellow on the outside, white on the inside, and an egg is white on the outside, yellow on the inside. Similar metaphors, coconut or oreo, are used for people of darker complexions who "act white".

While the term egg is usually one of pride for the egg in question, other terms involving the notion of acting like another race can range from mildly to highly pejorative. It ties in with complicated issues like racism, separatism and notions of racial betrayal.

Another, less known term is japoser . This phrase is little known, but used when one acts as if he or she were an authority on jpop and wants to learn Japanese just to translate lyrics.

A term related to egg which is pejorative is the term Wapanese, which is based on the expression Wigger. Wapanese deals specifically with a white person who is obsessed with Japan, often especially anime, and imagines him or herself to be an authority on Japan, yet usually lacks a real understanding of or respect for Japan. Wapanese tend to be middle class white teenagers or college students who feel alienated by Western society and imagine that they would be accepted in Japan.

A good or bad egg is also an English slang expression for describing someone as good or bad. The term first appeared about 1900 as slang of the public school and university for somebody pleasant, agreeable, or trustworthy (and also as “an exclamation of enthusiastic approbation”, as the Oxford English Dictionary defines it).

It is also associated with the late P.G. Wodehouse, who did much to popularise it, having presumably picked it up during his school days at Dulwich in the last years of the nineteenth century. He seems to have used it first in Something Fresh in 1915: “‘She isn’t going to sue me for breach?‘ ‘She never had any intention of doing so.’ The Hon. Frederick sank back on the pillows. ‘Good egg!’ he said with fervour.” But Wodehouse was pipped to the post in the literary immortality stakes by Rudyard Kipling, in his book Traffics and Discoveries of 1904. Good egg was at first just a humorous inversion of bad egg, which is also public-school slang, but from half a century previously. A bad egg was as thoroughly nasty a person as the literal bad egg was unpleasant to encounter.

Interestingly, "bad egg" is one of the few (possibly the only) English slang expressions that can be translated directly into Chinese, in which it is also slang and is understood to have exactly the same meaning (坏蛋, pronounced hùai dàn in Mandarin). Given the newer, racial spin on the term "egg" described above, this coincidence might be seen as humorous. It is unclear whether these two terms are cognate or simply coincidentally the same.