When naming your game file (when you are making your license plate), put in the following names. Hold L and R when you enter and confirm the name.

Look like the Chief - B1G1
Look like Rosie - ROSA
Look like Rosie in lingerie - HURT_M3
Look like a cop - FUZZ
Look like a police officer - FATT
Look like a SWAT officer - SWAT
Look like a commando - M1K3
Look like a female worker - HARA
Look like a male worker - HARA
Look like a female punk - B00B
Look like a male punk - MNKY
Look like a gangster - TFAN
Look like a boxer - BRUZ
Look like a gambler - MRFU
Look like a butcher - PHAM
Look like a biker - HAWG
Look like a S&M donkey - JASS
Look like Ancient Wu's concubine - TATS
Look like a pimp - PIMP
Look like a hobo - B00Z
Look like a corpse - J1MM