"Eww," Billy scoffed with a smile at the mention of girls and advice. But since he wasn't exactly sure that Bart was of the mind to deduce that he was only teasing, he offered a quick "I'm kidding," as they walked.
"Honestly... I don't know how much help we can be until we know the situation, but I'll do my best." Billy didn't even consider himself anywhere close to an expert on relationships. If he knew that Bart and Tommy knew each other as well as they did, he would have probably recommended a teen speedster to teen speedster talk. Of course, he decided against that almost as quickly as he thought it. It wasn't that he didn't think Tommy was a nice guy or capable. He just wasn't sure that Bart in his seeming funk was ready for the style of advice that Tommy might give. It might be better to come from a more... thoughtful voice.