Crisp

Crisps were, according to the eighth Doctor, a "highly salted" and "processed" potato snack. Typically, they came in packets. The Doctor once used a packet of crisps to feed the Nukaryote, and thereby escaped being absorbed by it. (DWM: Doctor Who and the Nightmare Game)

The Krillitanes used Brainy Crisps to increase the intelligence of children. (NSA: Code of the Krillitanes)

Later, when the Doctor first met twelve-year-old Kazran Sardick, he initially suggested that they should spend Christmas Eve "eat[ing] crisps and talk[ing] about girls". (DW: A Christmas Carol)