Meaning the act of hammering your own children in a sexual way.
Gadd reffering to Glam Rock star and convicted paedofile Gary Glitter's real name, and Hammer reffering to a sexual act.
One person to another.
"Is it true that he is a slightly deviant person?"
"I hear he is a hammers gadd"
etymology: (Dirty South hip hop culture) "hammers" refers to Starr Hammer custom hubcaps and "vogues" refers to Vogue Tyre custom rubber tires.
"Welcome to Atlanta, jackin' hammers and vogues,
back to the mackin' and jackin' the clothes, adolescents packin' a fou'." -Ludacris in Welcome to Atlanta
Translation: Welcome to Atlanta, stealing expensive custom cars, showing off your wealth (mackin') and stealing clothes, adolescents have 40-44 caliber pistols.