you cant do human farm bug anymore, fixed in patch. it was where you built a farm in a certain spot, near trees. your peasant would move to the other side. you could then just build the farm for no money and when you canceled it, you got 80 gold, 20 lumber. you could do this over and over again.
im not too sure on the BM invisible pull, but i think its where you windwalk, and you right click on a creep, and you could pull it to a tower. you just keep rightclicking creep, and the creep would try to attack the BM. since the creep cant see the BM, it just sits there while your tower eats it. you get tons of exp and good items that way early in game :/.