When Liz Lemon was trying to sneak out of Jack Donaghy's office on her knees in last week's episode of '30 Rock', she was seen anyway by Jack's ex-wife. As a half-hearted combination of an apology and explaination, Liz pointed out that the maneuver would have worked for 'Ugly Betty'.
I put the quotation marks around the name because I'm sure she was making reference to the ABC TV series. But of course, in Toobworld, '30 Rock' and 'Ugly Betty' co-exist in the same dimension.
So to keep the reference Zonk-free, we have to figure out a different meaning for "Ugly Betty".
I don't think Liz could have meant Betty Suarez herself. She more than likely was familiar with Mode magazine, and she might have known who Daniel Meade and Wilhelmina are. (This would be mostly due to her friendship with Jenna Maroney, who probably either knew them or was familiar with the behind the scenes machinations at Mode). But as for Betty herself, I don't think their paths would ever have crossed.
It's a stretch, but if pecking orders and the laws of the jungle were the same in all corporations, it could be that there are people working at NBC who have been tagged with cruel nicknames just as there were at Mode. And even though you would think the odds were against it, perhaps there was an "Ugly Betty" where Liz worked as well.
Like I said, it's a long shot, but it's better than surrendering to the Zonk.