This is something I've considered doing during the writing of RWBY watches Reviving Bionicle, specifically episode anonymous, but I'm only doing it since people have asked for it anyway. Might be fun, so lets give it a go.
"Whatcha got there Blake?" Yang asks, leaning toward her faunus friend.
"Nu-Nothing." Blake stutters.
"Its that fanfiction you were talking about earlier." Yang guesses.
"Well..." Blake trails off, realizing shes defeated. "Kind of, except I haven't really started yet."
"Oh, whys that?" Weiss asks from the desk, she is currently studying.
"Well, I just don't think I know enough about Bionicle. After all we only watched that fan show." Blake reminds them. At that moment the room started to get windy.
"Ruby, did you leave the curtins open?" Yang asks. Ruby looks away from her scroll and towards Yang.
"No?" She says also confused by the wind. After that a figure popped into existence. It was a scale Lego minifigure (Though they don't know that) with yellow skin, grey pants, a white and black striped tee shirt, and a black hat.
"Oh, its been... 3 years since I've crossed dimensions!" He exclaims while streching his back.
"What are you!" Weiss demands, clearly alarmed.
"Im just gonna auto correct that to who." The minifigure says. "I am The Robber. 'The' is included with the name. And I have been sent by Min- I mean CrossoverAddict67 to give you guys something." He says.
"So, do all these dimensions have ridicoulous names?" Yang asks.
"No, its just me!" The Robber exclaims. "Anyway, he said take as less time as possible, he doesen't like it when OCs take a big part in fanfics, so Im just gonna hand you this." The Robber hands over a cardboard box. "The note will explain everything." He then poofs out of existence.
"... Anyone know what he was talking about?" Yang asks
"I don't think we ever will." Blake says as she turns towards the box with others following suit. Ruby reads the note aloud.
'Dear team RWBY. It has been highly requested that you start reciving packages about Bionicle. These can be anything ranging from toys to games to video clips to ...music I guess. Don't worry about the man who just delivered it, he is one of my most trusted and in the past years, he hasen't done anything much. Hope you enjoy. -Crossoveraddict67. Ps. No I did not make Reviving Bionicle.
"So this Crossoveraddict is the one that sent us the mysterious package." Weiss deduces.
"That sounds like a username." Yang points out.
"Irrelivent. Lets open our first package." Ruby excitedly declares.
If you haven't read Team RWBY watches Reviving Bionicle, I suggest you read that first. If you haven't seen Reviving Bionicle by Suddenlyoranges, I suggest you do that before reading the previously suggested thing. Anyway, you can comment on what you want RWBY to react to next (I would perfer if it was in the 2001 era) but Toalorikan626 has first dibs with the toa mata.