The Good News presenter was speaking on fellow comedian Richard Herring's Leicester Square Theatre podcast when he recalled having to undergo an operation following an accident.
Howard described how he nearly had his thumb amputated after it became badly infected when he injured it on a fence.
Describing the experience of being under anaesthetic as "weird", the 32-year-old said: "You can see the words tumbling out of your mouth but can't stop them. There were two things I said."
He described the first as thinking he was a knight and asking a nurse to find him a horse in order to escape.
The second, he said, was "terrible", adding: "But I was under general anaesthetic, so it's allowed!"
He continued: "I pointed at this bloke who had just saved my thumb and was like, 'You're not allowed to be on my football team'.
"I don't own a football team! I was so gone I can't be 100% certain I didn't make that statement based on race. That's the worst thing. But it's not me, it's the drugs.
"That's why I can never take proper drugs - because a general anaesthetic turned me into a racist football manager! 'You just won't fit in, lad!'"
Howard appeared on Channel 4's Big Fat Quiz of the Year, which generated complaints to Ofcom for some of the jokes featured on the show.
The comedian also recently described the friendship between DJ Nick Grimshaw and One Direction's Harry Styles as "weird".