g-words could mean words starting with the letter g?.
g-dog and g-things, unknown to me.
Unless they too are for describing dogs and things that begin with the letter g. Like greyhound or garage.
A popular radio personality here in the U.S. uses,
"What are you doing that for G D it."
meaning, "What are you doing that for God damn it." =)
A g-man here in the U.S. is a term used to discribe a government man or a member of the F.B.I., a term used in the 30's, 40's and 50's more than today.