In a deleted scene in Drug Testing, it was revealed that Leo and Gino were the culprits of smoking a joint in the parking lot.
When Michael is looking for a way to frame Toby by placing illegal drugs in his desk he finds Gino and Leo in the Vance Refrigeration lot on their lunch break and asks to buy some from them. They hand him a bag of it and make him pay $500 however it later turns out to be salad (Frame Toby).
Leo finds Kelly and Erin dancing in the closet that used to be "The Michael Scott Paper Company" now converted into a cafe disco. He convinces Gino to go join them who is eating his sandwich on his lunch break. He seems worried about not being able to eat his sandwich (Cafe Disco).