Can anyone think of any aspect of American culture that would be weird to an outsider from another planet?
Another planet? Everything.
It really depends on whether the alien life form is carbon-based or silicon-based, don’t you think?
Keeping boxes of feline urine and feces in our homes? 
You could start by introducing them to Bush, explaining that he’s the “leader of the free world.” Then you’ll hear their equivalent of “BWA-HA-HA-HA-HA-HA!”
Then you can tell them how hot dogs are made.
Actually, it’s hard to think of anything that **wouldn’t **seem weird.
Then explain that we have a contest each year on our nation’s birthday to see who can eat the most of them.
I think the death penalty would confound them, as would a penal system that neither deters nor reforms criminals. Welfare may either appear woefully inadequate or overly available.
I would think the fact that we revere actors, singers, and other aspects of pop culture over our great thinkers, scientists, and philanthropists.