"Bonk is a video game character from NEC's TurboGrafx-16 console. Known in Japan as "PC-Genjin" (ＰＣ原人, PC-Caveman, a pun on "PC Engine") and as "BC Kid" in PAL territories, Bonk was a mascot for NEC's console, though some Bonk games eventually saw releases on other consoles as well. A large-headed, bald caveman, his favored form of attack is the headbutt. The "PC" part of his Japanese name stands for "Pithecanthropus Computerurus", a fictitious species name for Bonk."
Source: Wikipedia, "Bonk_(video_game_series)", available under the CC-BY-SA License.