Básicamente, el significado es escupir. Pero escupir con gran fuerza. "To hock a loogie" no es un esfuerzo débil. ¡Esa saliva, hay que dispararla! As for using it in phrases, it's pretty straightforward. It's sometimes used to hock a loogie off something. For example, in the movie Titanic there's a scence where Jack teaches Rose to hock a loogie off the ship.

hock a loogie? Just means spit, doesn't it? It's American. We say "gobbed" (for spat) "gob" (for spit). Gob means mouth, "shut your gob!". He punched him in the gob etc Sometimes people say, "grem" as well but I have no idea why.

Theres really not that many sentences you can make up! I hocked a loogie on to the bar. She was in the middle of hocking a loogie into the air when she was hit from behind

There is an added connotation to "hock a loogie." It means more than just "to spit." To be graphic, it means to pull up the thick, gross, yellowish or greenish mucus from your nose, throat or lungs and to spit it out with force so that it shoots through the air. The fun of "hocking a loogie" doesn't come so much from it's linguistic use. The fun comes from actually doing it. :P