Acceptable use of the term is based not on whether you have privileges but whether it has a legitimate reason to be there. Personally I don't find STEVE URKEL SAID NIGGA LOL IM HILARIOUS at all amusing because the entire punchline seems to be that Steve Urkel said nigga. I like my humor to be clever. Honestly, if you're not good at humor, don't try to write it; no jokes are a LOT better than bad jokes. I know I'm not good at writing humor, so I don't set out to write things that are hilarious.
Dude, it was one line. And you don't even know the context of it. Steve Urkel is a black guy, Steve Urkel said "nigga", legitimacy confirmed. Black people use the word among themselves, and part of writing a believable black character is use of that word.
It has nothing to do with racism or whatever, he didn't use the word in his game to be hurtful, he used it to make the character believable and for comedy. Whether you think it's funny or not is not the point because you are not the standard of what's funny and what isn't. Others may think it's funny.
Don't forget humor is based on opinion. You might laugh about stuff I think is stupid and vica versa. Sure there are bad jokes in general, but this is not one of them.