Abbreviation for Machine Gun Kelly, a white rapper based out of Cleveland, Ohio. He has 3 mixtapes- 100 Words & Running, Lace Up!, and Rage Pack. Lace Up is his most popular and is also a term used by MGK fans. He has lots of tattoos, but the one he is most known for is "EST 19xx", which means Established 1990, the year Kelly was born.
Person 1: What're you listening to, bro?
Person 2: Just some MGK!
Person 1: Hell yeah! Lace up!