Liz Lemon is the coordinator of a rock sketch as seen in Sesame Street episode 4168. She has ordered 30 rocks, the delivery of which are late. When they arrive, her boss Jack looks over her shoulder to ensure that there are indeed 30 rocks rather than fifty, one hundred or three. To appease her boss, Liz takes the time to count the rocks.
The character is a spoof of Tina Fey's 30 Rock character of the same name.