The Borscht Belt is a refernce to the has-been resort strip along Route 17 in New York State just below the Catskill Park. Rumor has it that plans are in place to rejuvinate the once-happening area.
Vegetable soup mostly made out of beets. Originated in Eastern Europe. Called barszcz in Polish and באָרשט in Yiddish. Usually served with sour cream. Sometimes it has meat in it.
The Eastern states with predominantly-large poor Orthodox Ashkenazim (refujews migrating from Russia, hence the 'borscht' tomato soup).
Some argue that this name is giving humorously to the summer vacation resorts of up-state New York, but it has grown since to include most of the eastern states, too.
Having vaginal sex with one's girlfriend/wife/fuckpuppet while on her period. Especially relevant if your female sex partner is a Germanic/Slavic minx.
"So how was your night?"
"Not bad. Genevieve was on her period, but I still got to stirring her borscht, bro-man-dude."