Worcester sauce Wheat Crunchies at the moment, although salt & vinegar Discos are a time-honoured favourite. INSANELY strong flavouring, almost takes the roof of yer mouth off.
As an aside, I had a bag of prawn cocktail Skips the other day, and was rather disappointed to discover they seem to have lost a lot of their flavouring. Very bland these days (although perhaps the Discos have destroyed some of my taste buds).