The actor, who played Boy George's ex-boyfriend on last week's Worried About The Boy, said that it is "unhelpful" for them to "pretend" to be straight in "the public eye".
He told Gay Times magazine: "What I don't like is people who are gay and pretend they're not and they're in the public eye.
"I think that's really unhelpful, and I've known a couple of people and that's been a bit of a bugbear for me, and I don't think that's very cool.
"There's a couple, who both appeal to a young audience. Two people I can think of, one in music, one in acting, [though] it's not my place to out them."
Horne also fought back against suggestions that his sketch show contained homophobic characters.