Tammy is a high school student that blackmailed Dennis into going to the prom.
At Paddy's Pub, Tammy aggressively approached Dennis and told him she was 18 and liked to party. He told himself and her that he wasn't interested because she was too young. She later appeared at his apartment and blackmailed him into taking her to the prom by threatening to tell the police Paddy's was serving beer to minors. At the pre-prom party at Paddy's, a very seductive Tammy approached Dennis, and Mac and Charlie told him that sleeping with an 18 year old isn't gross. His attitude changed toward her, but Trey took her away to the prom. She was using Dennis all along to make Trey jealous. ("Underage Drinking: A National Concern")
- Tammy is portrayed by Jaimie Alexander, known best for her roles in the movies Thor and Rest Stop as well as the TV show Kyle XY.