a older person (whether in their late teens or beyond) who preys on young barely pubescent teenybopper whether because of their low self esteem, or because 'grownups' seem cool to this younger age group. Teenyhoppers can usually be found at Disney Channel star concerts as well as Twilight movie premires. Teenyhoppers mostly reject partners who are around their age group as they are too mature and theirfore unattainable for their liking.
person 1: Isn't Tom is college?
person 2: yeah, he's a Junior why?
person 1: I just found out that his new girlfriend is barely a highschool freshman!
person2: ugh, what a teenyhopper!