jazz hug

euphemism for sex; derived from an animated version of the "hug" emoji 🤗, which appears to do "jazz hands" (waving hands back and forth rapidly)
Denotes a hug that is "jazzier" than a normal hug, and hugs are already quite close and intimate so the next step would logically be fornication

Those two seem pretty wrapped up in each other; they best watch out, they'll be giving each other the old "jazz hug" before long