Flirting with best friend?

I've been with my boyfriend for over 2 years, and I love him dearly. I don't have feelings for anybody else. My best friend is a guy. I've been really good friends with him for about a year now, and I love him so much, but it's strictly platonic. He's like my brother, but we're closer. He's also like completely in love with another of his best girl friends, and they're going to be together in a week or two. So there's no feelings on either side. We see each other almost every day in cl, and we flirt all the time. We'll poke each other and hug and joke around, and most of the people in that cl think we're together. He came over to study yesterday and we had a major tickle fight. We even laugh about how much we do flirt, and we both know that it's perfectly harmless. If it was anyone else, I'd feel bad, but my boyfriend knows how close we are and likes the guy. And the other girl knows about me, but we haven't met. Is this bad? We just kinda flirt with each other cause we know we shouldn't and can't flirt with anyone else.