A pgm is an abbreviation for:
Pro Game Master.

PGM is a word, which is said in french, but stands in english, you can say it in english if you want, if you're a ♥♥♥. so this is how you say it:

"Peh-Jeh-Em"
PGM is usually used for games, "I am very 'Peh-Jeh-Em' at this game", or you can use it for other crap, "How'd you do that you lil 'Peh-Jeh-Em' "

A small describtion of PGM, possibly more to come.