(CNN) -- Neil Patrick Harris isn't a foul-mouthed rocker -- he just plays one on Broadway -- but he's had some people fooled.
The 40-year-old actor is starring in the musical "Hedwig and the Angry Inch" as the titular German transgender performer, and he's so immersed in his character when on stage that not even an excited fan can pull him out of it.
He proved that at an April 19 performance, when, according to the New York Post's Page Six, one supporter yelled out "I love you, Neil!" while the actor was on stage as Hedwig. Since he was in the middle of a show, Harris swiftly responded the way Hedwig would respond: "I'm doing something up here, motherf****r!"
The Post reports that the audience loved it, but apparently not everyone has. On Twitter, Harris has had to clarify that he wasn't swearing at a fan; he was playing a part.
"Take a breath," Harris told an angered observer who chastised the actor for his "outburst." "I'm playing a character. Who is harsh. That's the show. That's Hedwig."
"Hedwig and the Angry Inch" is the kind of production that welcomes improv, and audience participation can be used as a springboard for that. When the Harris fan confessed her love for the actor on Saturday, Harris worked it into his act as he's supposed to, his rep tells Gossip Cop.
"When the fan initially yelled, 'I love you, Neil,' Neil (as Hedwig) then responded, 'Who's Neil? I'm not Neil.' He then looked over at Yitzhak (portrayed by Lena Hall) and said, 'Are you Neil? You better not be Neil,' followed by Hedwig then offering the quote in question. It was all done in good fun, and fully in the context of the show."
"Hedwig and the Angry Inch," which has been running preview performances, will celebrate its opening night on Tuesday.