Topsoil is a word used to insult someone. Similar to calling someone a "dirt sack" but is much worse. Topsoil is worse than be being called "dirt" because top soil is what you walk on.
A chewing tobacco "dip" (either in long-cut or pouch form) put it one's upper lip. This is commonly done to reduce the need to spit, as less saliva comes in contact with the tobacco.
“I ate some really spicy food yesterday and I was ass-blasting top soil that was spicier than you could imagine.” - paraphrased from Rachel Quirky Schenk, co-host of “The Infinity Podcast”
