The point is that you should avoid doing or even saying anything if you’re not certain of the implications. As cool and casual as it may make you feel, it’s probably best not to suggest to your boss that you hook up later on this evening. Maybe not smart to ask your teenager whether they hooked up with any of their friends last night. Might not be wise to say wistfully to your neighbor that you wish you could hook up more often.
So what DOES hookup mean? Anything and everything, apparently. Maybe if we get under the covers and turn out the lights for long enough, the phrase and all its implications will just go away.