In the season 1 episode "Richie's Song", the guys are all hanging out in Doug's garage. At one point, Spence announces that he found some M&M's in the car and asks Doug if they are alright for eating. Doug then asks if they are the regular kind or the peanut kind. Spence replies "peanut" followed by "they taste weird" meaning he had eaten one. In a later season of the show, Spence is babysitting Deacon's kids. They call him the "Scared-inator" because he refuses to eat peanuts due to his allergy.

Hm...