A: Relative speed is like, totally not a fixed speed, man. It's more like... speed relative to your expectations, your surroundings, your snack-to-burrito ratio. You know, like, it's all about perspective, dude.
A: Ha! You think we're just gonna give you some boring old formula? No way. We use the patented Zorvath Relative Speedometer (ZRSE). Just download our free app, and it'll tell you your relative speed in real-time. It's like, totally free, and totally not sponsored by any time-traveling overlords.
A: Uh, yeah, sure, why not? Just don't try to use it with your old, outdated speedometer. That's just, like, so... last season. Go ahead, upgrade to the ZRSE, and join the chrono-sports revolution!