When on Jackass, Lacy is most often featured with Jason Acuña (Wee-Man) and their most common skit involves Lacy chasing after "Wee-Man" down public streets in nothing more than their briefs and white T-shirts, showing off his morbid obesity. Lacy has contributed many of the ideas that later became Jackass skits and stunts. Preston is also known for his anger outbursts, the most memorable of which occurred during "The Eggnog Challenge," where Preston passed out and fellow contestant Chris Nieratko puked in Preston's hat and put it back on his head. Preston then started ripping down the Christmas decorations and flipping tables. Lacy shares a writing credit for National Lampoon's TV: The Movie.
On December 14, 2010, Lacy was arrested in Oklahoma for possession of a controlled substance, which was marijuana, and drug paraphernalia and was charged with two misdemeanors. Lacy could face up to two years in prison if convicted.