‘CosmoGIRL!’ Parties Like It’s Freshman Year All Over AgainLast night saw loads of magazine parties: The blazered GQ staff boogied down at Passerby, Wenner Media rocked out at Madison in the meatpacking district, and W celebrated its continued existence at Death & Co. We didn’t go to any of those, because we were at New York’s own fiesta at the Cub Room. Unfortunately, we can’t tell you much about that, partly because we’re not allowed to but mostly because we can’t remember much — except that we were pleased to learn that our co-workers like to party. And that Jessica Coen will do the splits if you ask her nicely. But we can offer you a report from inside the CosmoGirl soirée, held at the decidedly un-girlie Rumours, a tinsel-decked, wood-paneled sports bar on Eighth Avenue in midtown.