Each ghost has a nickname. The nicknames are based on characteristics. Here is a full list:
Original Game Nicknames
Pinky is about the same speed as her ghostly friends but is slower than Blinky, so she is known as Speedy.
Inky attacks from afar, so he may possibly be shy, scared or Bashful.
Clyde is always somewhere else poking around, so he could be addressed as Pokey.
Pac-Man Arrangement Nicknames
Note: Due to the Clyde and Blinky error, the red ghost is considered Clyde and the orange ghost is considered Blinky in this game. They will still be named properly though.
Blinky can irritate Pac-Man since he constantly follows him, so he would be an Urchin.
Pinky is playful and cheery and happily hops around as a bunny as her special power, so she would be considered one who likes to Romp.
Inky has his own unique way of capturing Pac-Man, so he would be a Stylist.
Clyde doesn't mess with Pac-Man a lot, so he is a Crybaby.
Kinky's nickname was never translated from Japan to North America, so he is just ?????, an unknown nickname.
These names are not official nicknames, but just labels based on behavior.
Kinky is able to create clones and pair up with the ghosts, so he would be a Scientist.
Sue is Aggressive since she chases Pac-Man no matter what.
Funky jumps almost as high as Pac-Man, so he is an Airborne.
Spunky jumps exactly as high as Pac-Man, so she is a Vaulter.
Kinky may also be called Fearful because he always looks scared.
Sue, Kinky, Spunky, and Funky's nicknames are unofficial.