Stephanie was a schoolmate of 11 year-old Sam Winchester with whom she had a crush on.
After Sam and Dean were shot by vengeful hunters, Sam found himself at Stephanie's house having Thanksgiving dinner with her family.
Stephanie's father told Sam she'd been talking about Sam constantly since he'd enrolled at McKinley two weeks prior, which indicated that she had a crush on him, in addition to the smile she gave him. After snapping at her dad to shut up, Stephanie proceeded to reach over and squeeze Sam's thigh. Soon afterward Sam looked up and saw Dean standing near, casting a disapproving look, and asked what he was doing in his dream.
Sam and Dean soon came to the realization that they had died and were in Heaven reliving some of their respective "greatest hits." Dean was surprised that "playing footsie with brace-face" was on Sam's hit-list, until Sam clarified that it was as his first real Thanksgiving that he remembered it, which contrasted from the "bucket of extra-crispy and dad passed out on the couch" holidays he and Dean experienced as kids.