Slumming Defined
Hang out with someone of much different socioeconomic status usually for the reason of wanting to look cool or to feel more connected with another culture very different from one's upbringing. (Via Urban Dictionary)

Nicole Kidman was caught slumming it at the CMA's last night, alongside her sexually ambiguous husband Kenny Chesney Keith Urban. See Nicole? This is why Cosmo advises against "marrying down." Maybe it's cute now, but before you know it you're spending Thanksgiving at his Mom's double-wide -- with his Step-dad getting drunk and picking fights with his uncle, and everybody uses paper towels as napkins and smokes at the dinner table. Or, you know, getting stuck attending the Country Music Awards.