Just how sinful is our favorite show? So much so that Gossip Girl cast members may be starting to get involved in some off-screen drama.

An E! Online source says they saw Blake Lively hanging out at New York club Southside Friday night, hooking up with a random blond - definitely not dark-haired Penn Badgley, whom Blake's been dating for the past year or so.

Says the N.Y. source, B.L. came in around midnight with a group of chums and was "too busy making out to dance or drink." And that's not all.

The next morning, Blake Lively and Penn Badgley were spotted having one awkward brunch at Norma's restaurant at Le Parker Meridien hotel.

"They both looked miserable," says a fellow diner who spotted the unhappy Gossip Girl twosome Saturday morning. "He did not smile once."

Neither Lively's nor Badgley's reps commented on this rumor.

Elsewhere, across town on the same night, a Gossip Girl guy named Ed Westwick was seen at Studio at Webster Hall for his friend's DJ gig.

"He was really drunk," says a fellow partygoer of the British actor and rocker. "He just went back and forth between the bar and backstage."

Gotta live the rock star life! Ed reportedly partied well into the night sans rumored love interest and Gossip Girl co-star Jessica Szohr.

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.