"Luggin' It" refers to someone who is lugging a large penis around, or possibly lugging multiple girls around. If someone is luggin' it, it means they are pimping it or being a pimp.
Dude, check out Ross making out with those two chicks over there! That fool is finna luggin' it!
We finna lug it all night tonight with the ladies.
Jeff: Just one more song bro, then I just gotta put a top on, find my keys and I'm good to go Andrew: Quit lagging it out you wasteman
Jeff: Aight chill man, you know I'm the lagmeister what do you expect bro