Live Together, Die Alone, Part 1 - S2-E23
Factual error: The prison Desmond is released from looks nothing like any British prison, let alone the British military prison (the "Glasshouse"), which is more of a training camp than a traditional prison. The guards wear no cap badges on their berets (all British service personnel wear cap badges) and their berets are worn almost vertically on their heads, whereas British berets are pulled hard to the right. The NCO who releases him is credited as a "master sergeant" in the episode credits - an American rank which has never been used in the British Army.
Answer: He was eating a peice of an orange with the skin still on.
XIII