I would think this was cute. It's low-stakes, playful boundary pushing that indicates flirtatious interest.

I'm a girl, so ymmv, but I'm a huge believer in communication, enthusiastic consent in all things, and boundaries. This sort of breaks all 3 of those things, even though its fairly innocuous. I would be much more into it if there was explicit communication about it. "Could I try some of yours?" - this kinda doubles as a great way to check boundaries and consent (of you drinking from my glass), and also as a sort of double entendre if the vibe is there.

When I was younger, and as long as it wasn't my first beer, I'd have interpreted that as "I want some of what you've got" and been flattered. Probably some quip like "okay this round's on me but you're getting the next one".

But not everyone's flirtation styles line up, so be(e) kind to yourself. Make this time a joke to prepare the guy next time, and use their reaction to gauge whether the flirt will pay off (use your best judgment and be safe!). I'm glad you went out on a limb, and I think there'll be someone who can roll with what you're bringing

High risk high reward honestly.

Depending on my mood I could vary from very turned on to grossed out and germophobic.

This is funny to me! I am definitely not the person to ask, I am not in that zone or area, but to me this is definitely a flirty sign. Granted, my wife loves beer as much as I do and we love sharing it and tasting, so if she did that to me in a club I'd assume she was flirting. (If she drank half my beer now then I'd be upset). Maybe some weird masculine "Breh mreh girls don't drink beer" BS?

The only thing I can think of as an old man is that post-covid, it's definitely not very sanitary, and maybe that's what scared them off? However, I wouldn't be going to a club if I was worried about that. Thinking about how many people's sweat you got on you that night...

Oh, to bring the tone down I should say be careful of drinking from drinks that aren't yours though. My wife was actually roofied. I was luckily there just in the bathroom when it happened, but that was the scariest night of my life. Some absolute asshole drugged her, I walked up and he pissed himself and ran away. It shattered all of my illusions about safety in clubs. So, maybe it would be best to just have your own...

It's gross. I don't want to make you feel insulted, so I'm going to try to be gentle with this, but if a girl drank my beer without asking I'd think that she has poor boundary recognition and that her... hygiene preferences, are incompatible with mine. It would be an immediate and massive turnoff.

I'm sure some people like that, but even if I did like it, it would be a red flag that you did it without asking.

I wouldn't consider that desperate or easy, but I'd be icked out by it. I'll buy somebody a drink, but I don't want to drink a stranger's backwash.

I'm in the UK, and have been with my wife for about 20 years, so the context might be different, but when I was young and single, that was a big red flag.

I know it's not the way you meant it, but back then, the girls who did that were generally hard work. There was probably an 80 / 20 chance that they expected you to buy them drinks all night, and were just doing it for the free drinks. If you didn't buy them, they'd grab the next guy who looked daft enough to fall for it.

Unfortunately once you've been caught out by a few people like that, you tend to be suspicious of the genuine people too.

Probably the best thing you could have done afterwards was to buy him a drink and say something like, sorry, I didn't mean any offence, and leave him alone. Let him make the next move if there is one.

I don't think gender is of much help here, apart from your preference/orientation when flirting.

Personally, it would've put me off a bit if someone I haven't seen before took a drink out of my hand without asking, because my only way of dissenting would rely on an unprepared attention and strength game - would I've been asked (person pointing on the drink or verbally asking), I could say or gesture a yes (Only yes means yes). Asking is sexy.

Weird, I wouldn't be put off by that at all. It shows you're comfortable with someone. I'd actually like it if someone does that to me, it makes me feel trusted.

Some people can be pretty germophobic though, but on the other hand if you're flirting you probably end up (or desire to end up) kissing the person so in the scope of that it's not really a big thing.

But anyway, people are different, clearly for him it was a problem but it definitely isn't for me. Don't worry about it, you sound like a nice person! Sometimes people are just incompatible.

@appledinosaurcat I can imagine for some people it might give a strange vibe around respecting consent and boundaries.

It's bold, at least. You should have asked before you did that, many people view sharing drinks as about as intimate as kissing. I could see it working in some circumstances and being playful, but in the future if it doesn't work you should probably buy the guy a replacement beer lol. Live and learn.

Some of the responses here have me laughing at how uptight they are. What you did was perfectly normal, he was rude and you're best off not thinking about him ever again. Fuck that guy!

I don't like sharing my plate with family.

I wouldn't have dropped you like that, after a single offense. I would have made it very clear, that beer was now yours, and I would not be drinking any more of it.

If you did something like that a second time that night? Yah. Then it would've been over.

I'd think it was normal

I'd personally be a tiny bit put off, but it certainly wouldn't have been a dealbreaker for me.

Edit: Having reflected on it, I think that, if the vibes were good, I wouldn't have minded at all. I suppose it's just one of those things that you feel out in the moment. Don't let it bug you too much; you're a cool bee. :)