Maybe it was Kryten's punishment for leading them all on the wild curry chase at Lister's request (who had already been punished with a no-holds-barred beatdown - OK, it was actually Spare Head 2 without a guilt chip, but nevertheless).
Rimmer: We might as well have a melon in command. Kryten: I thought we did sir. *Rimmer gives Kryten a death glare* Kryten: Oh I see. I'm sorry sir, the voltage must have damaged my comprehension chips.
