This is pretty much my favorite gif-set right now, and a good example of the active backlash going on in internet circles that we were talking about.
Let's be real, acting white is acting "right," and people of color get complimented for doing it. We are actively encouraged to look down on those that don't. From 7th grade til graduation I lived in Olive Branch, Mississippi. I was usually the only Hispanic person in my class. Pretty much all of my friends were white. The few that weren't, like me, tended to tone "the otherness" down. One of my fellow Latina classmate went as far as never speaking Spanish in front of anyone while in school.
And for a really long time I thought this was absolutely normal. I thought that that was just something you had to do to get ahead in life: learn to do things "the right way."
And right there is the difference between appropriation and assimilation. I was trying to change how I dressed, how I talked, what I ate because I thought I had to to fit in. Appropriation on the other hand is what white people do when they try on other cultures as a costume. It's when people dress up as a "sexy geisha" for Halloween, or when people do this on Cinco de Mayo
(Sidebar: why in the world do Americans even pretend to celebrate Cinco de Mayo? How did this even happen? Even if it was Mexico's independence day [which holy hell, it was a just a battle the town of Puebla won against the French; no one outside of Puebla celebrates it in Mexico], why in the world would America feel the need to celebrate another country's independence day? No, "people just want an excuse to drink" is not in any way acceptable)
I've also seen a lot of people that genuinely love another culture and want to take part in it. However, most of the time even they tend to exotify a that culture and sigh sadly that theirs isn't as "exciting/beautiful/interesting" etc. A good quote that sums it up is David Wong's line, "But remember, there are two ways to dehumanize someone: by dismissing them, and by idolizing them." I've also seen way too many white people lament that they don't have a culture, which is always baffling and mildly upsetting for me to hear. They might not mean any harm, but it means that they see white culture as being the standard, the norm, so predominant that it is invisible to them. America damn well has a culture because the rest of us bump against it every single day.