The model revealed that while she's outgrown her Zac infatuation, she did get to meet another big crush just last year in an emotional moment that led to some tears.
Reminiscing about the first time she met rocker Alice Cooper, Jackson said, "I was telling him 'I love you so much. I always listened to you. I grew up, like, loving you ... ' and I was close to tears. I started watering up."
Fallon joked, "You're almost crying now! Oh my gosh!"
After all the serious talk about young love, the teen and the late night emcee lightened things up with a game of "Egg Russian Roulette" where they each took turns smashing a random assortment of cooked and raw eggs on theirs heads.
See who narrowly beats out the competition in the clip at the top.