To have or get a lot of booty(girls), or to form a long line of girls you will get "booty" from.
Yo frank I started my booty train last night!
Oh with who?
Kim now I'm moving on to get more booty
It is like a regular train (ie a whole bunch of dudes nailing a drunk chick) but in the butt
We ran a booty train on that hoe!!!, She rides the booty train or can we run a booty train on you?