Results after 3 days of this very non-scientific test:
The "juvenile" GIFs I made didn't perform much differently from other "more mature" creations at or around the same period of time. I would chalk any difference up to factors which were not controlled for.
One of my other memes just hit front page of fun and it was based on the lyrics from a boy band song from 1999.
Conclusion: Nothing in this very small sample size conveyed that appealing to juveniles in the fun stream confers a marked advantage.
