Such behaviour isn't exactly the kind of paranormal activity explored in his new film, Red Lights, but it's as rum a business for an Irishman as it would be for a Scot, a Welshman, or even a Frenchman.
Yet, as with the paranormal, it's a case of seek a rational explanation and ye shall find.
"I would never shout for England but, because of the handball with Thierry Henry ..."
Ah yes, that handball in the 2009 play-off between Ireland and France that cost Ireland a place in the World Cup. Normal supporting service will presumably be resumed when Roy Hodgson's team take on Sweden today.
In Red Lights, Murphy, 36, plays a physicist who works with Sigourney Weaver's psychologist to prove that where there are supposedly paranormal occurrences there's fakery at work. The duo's biggest challenge arrives in the shape of Robert De Niro's Simon Silver, the best in the psychic business.
The part of a doubting scientist suited Murphy's attitude to things that go bump near a ouija board. "I'd definitely be a sceptic and wouldn't waste my money on stuff like that. Not my thing. Prove it to me then I'll believe it." But as he says, it's a massive industry, particularly in America where the film is set.
As with the England aberration, the reasons he took the part in Red Lights (the title is taken from the tell tale signs that fakes emit) are easily unearthed. First, there was the Spanish director, Rodrigo Cortes, who scored a huge hit last year with Buried. Murphy knew him from this, and a previous film, The Contestant, and admired his style. There there were his co-stars, De Niro and Weaver.
"They're two of the greatest actors of their generation. Growing up, before I even thought of being an actor, I used to watch their movies and they were heroes of mine."
De Niro has a reputation for being shy on set. Murphy found him to be "a man of few words" but they clicked nevertheless. "We chatted and went for dinner and just did the normal things you do. It's very hard to separate his legacy from him and the way people treat him everywhere he goes. But he's a really genuine and warm man."
Besides dinner with De Niro, he spent time in Barcelona, where the film was shot, with Weaver. The Ghostbusters legend has strolled some strange cinematic streets before, albeit for more comedic purposes. Murphy, too, previously took a walk on the weird side with Christopher Nolan's endlessly inventive science fiction adventure, Inception.
Given how much it tested audiences, much to fans' delight, I wonder if the cast felt equally puzzled while filming it.
"We'd read the script, all of us. I read it several times; it was quite dense and quite hard to get your head around. Particularly when it's written, it's hard to visualise it. But Chris had lived with that story for 10 years before we filmed it, he obviously knew the thing so well. He's such a consummate filmmaker and we all deferred to him, just trusted in his vision of it, and it paid off."
Any particularly weird moments? "Underwater acting wasn't something I'd done before," Murphy laughs. He had to learn to ski as well.
"[Chris] really pushes the envelope and he wants his actors to do almost everything they can and use as little green screen as possible."
Murphy, born in Cork in May, 1976, met the British director when he auditioned for the lead in Batman Begins, a part that eventually went to Christian Bale. Murphy, however, did have the consolation of winning another part, as The Scarecrow, and got to try on the batsuit. "It was a bit sweaty."
Besides Nolan, Murphy has worked with other noted directors, among them Danny Boyle, with whom he made Sunshine and 28 Days Later.
"I enjoy that intense filmmaking, he pushes the actors, and I like pushing [myself] to the limit. Both those films were very physical and extreme. Danny enjoys that; I suppose we both have a taste for that. There are very few directors around who can excel in every genre and Danny's managed to do that."
In addition to Nolan and Boyle he worked with Ken Loach on the Palme D'Or winning The Wind that Shakes the Barley. Loach's Irish war drama caused controversy in Britain at the time, with some commentators attacking its portrayal of the British.
"There was a couple of silly articles written in Britain about it. In Ireland it really touched a nerve with people. It was 90 years since the civil war and still those wounds hadn't properly healed or were just healing over when this film was made."
In Ireland, says Murphy, it was a success with audiences across the age spectrum, a film that both grannies and grandchildren went to see.
Reviewers, as they always seem to do when Murphy appears in a movie, tended to focus on his large, piercing eyes. Is he sick of people going on about his peepers?
"People mention it but there's very little I can do about it." You sound like an idiot if you start talking about your features, he says.
"I've never felt it's helped or hindered me. You hope it's your abilities or your work that gets you the job. That's what you try and concentrate on. You try not to think about the other stuff."
He was back in Cannes this year with Rufus Norris's drama Broken, which Murphy describes as "kind of like a reimagining of To Kill A Mockingbird, but also not". It is undoubtedly moving he adds, the kind of film which has you leaving the cinema feeling "altered".
Inception, Red Lights and next Broken, altered states are becoming a home from home for Murphy. Just as well, games against France aside, he'll always know who to support at football.
Red Lights is out now.
