Underagebait

A combination of underage and ragebait, when someone on a forum pretends to be too young to know anything about what’s going on, for the sole purpose of pissing people off.

Not to be confused with jailbait, which is when underage people (mostly girls) try to seduce grown men (and women, presumably) online.

Crappy example of an underagebait post: hi guys im 8 and whats a pac man?