The Brief: To hookup, hook-up, or hookup means to engage in intimate and/or sexual activities with someone. A hookup is a person who someone has hooked up with. A hookup can also be a person who sells drugs, or the act of exchanging drugs.

DEEP DIVE
In the past, to hook up meant to meet up or get together, but now it has a much more specifically sexual connotation. It can refer to sexual activities including but not limited to kissing, oral sex, or intercourse. It usually refers to short-term, mostly physical relationships. People who are “hooking up” can also have romantic relationships with each other.
Hook up, hookup, or hook me up can still mean to put two things together, to give someone something, or for people to get together in a non-sexual way.
In that vein, a hookup can also refer to the exchange of drugs. A plug can be a “hookup” who can “hook someone up” with drugs.
How to tell what kind of “hookup” someone is talking about:
Even among those in the know, differentiating which definition of the term can be difficult at times. The best way to clarify is to use context clues and to ask directly if needed.
The last time a guy invited me to Netflix & Chill I said “Let’s watch Coco!” because I hadn’t seen it so instead of hooking up with him I just sobbed and apologized for an hour.
— Jessica Michelle Singleton (@JMScomedy) September 11, 2018
first rule of holywoo never hook up with an intern seond rule dont fall in love
— BoJack Horseman (@BoJackHorseman) September 11, 2018