Adrian Johnson, from Leeds, tweeted a photo of the McVitie’s milk chocolate digestives that had a best before date of 15 May 1999.
“Think I’ve just eaten a biscuit (from a packet given to our kids while trick or treating) that went out of date 18 years ago,” he wrote on 31 October.
Speaking to HuffPost UK, Johnson said the biscuits had “just an awful, gone-off, long-lingering bad taste.”
Johnson, founder of PR agency UMPF, said he thought the first mouthful of the biscuit was “weird”, but it wasn’t until his second bite he knew there was something definitely wrong with them.
“So I sniffed them, looked at the biscuit side, which was quite white rather than the usual brown-ish colour, and it was then that I checked the sell-by date,” he said.
“That second bit ended up in the sink and I had to rinse my mouth and brush my teeth. Pretty gross.”
Johnson explained this was quite late in the evening, so he didn’t go round to the neighbours who gave his daughters the biscuits.
“I might pop round tonight when I get back home,” he said. “More for their sake, than to complain, as who knows what else they’re keeping in their cupboards.
“My kids, Poppy and Eidy, found it hilarious this morning when I told them the story, as they were asleep when it all happened.
“They did point out that I shouldn’t have been pinching their Halloween treats in the first place!”