[Chill Phil]

Copied and pasted from a google search:

First released as "Puck-Man," the name was later changed to Pac-Man. The original Japanese name was Puckman, which evolved from the Japanese word paku, meaning "chomp." Given the closeness to a certain explicit four-letter English word, a lot of arcade operators at the time were worried that vandals would alter the letter P. Eventually, "Pac" was suggested as an alternate name. Hence the name "Pac-Man" came to be.

Interesting.