Slang term for the drug Crystal Methanphetamine, also known as: Speed, jab, ice, crank, dope, shard, wigg, sketch rock, tek.
A synthetic drug synthesized in 1887 by a German Chemist (L. Edeleano)
"He smoked so much gak he can't even blink, let alone fall asleep."
"I was so tired earlierthis morning, but gak's got my back!"