Sleeping with my bestfriend

I've known my best friend for about 5 years and every now and then we make out or fool around. B ut most the time we just go to the bar and shoot pool for several hours.

The few times we do stuff though it's just so sexy and turns me on.. but I don't ever see a relationship with him nor him with me...we're just really good friends. We do fool around sometimes when we are casually dating people but NEVER when we are in serious relationships.

Is this bad ?