Gygmomd pronounced gigamom is an acronym for "Got your grandma on my dick" phrase that became widely popular in the hip hop world thanks to the song "Rack City" by rapper Tyga. This phrase can be used in a myriad of sentences and daily life situations, including and not limited to an insult to a person or in a "friendly" manner. Older than cougar age woman who still want "game" can also be consider a gigamom.
A: Nig, that girl ain't tryna chill with your ugly ass
B: Gigamom nigga...don't need her anywayz
A: I kicked your ass on halo
B: Gigamom nigga... I was busy with your grandma.
A: Look at that old lady with skimpy clothes
B: Bitch be gigamom
A: Look at that granny talking to that younger muscular guy.
B: Gimamom status bitch!