I've recently made friends with two men, A and B. I met A through mutual friends and then A introduced me to B. We all got on really well, sometimes I would hang out with A and sometimes with both A and B. We don't know each other that well, so most of our time is spent on superficial subjects and making each other laugh. We're all pretty busy so we only meet up maybe once a week and we WhatsApp every 2 or 3 days, not as a group chat, that's just how often I talk to them. I imagine they talk and meet up with each other more often as they have been friends for much longer.
Just before Christmas I was invited out with them and another mutual friend but I couldn't make it. I did text A that evening to ask how things were going and if they had found a good pub. Just three short messages. A few hours later, I get a voice message from A's phone (but B's voice) replying to my messages saying "It's none of your business" and I could hear the other two laughing in the background. Then a text saying "Whose voice is that?". I thought it was a bit odd and I felt a bit stupid, so I didn't reply.
The next day B text saying "you're not upset about my message, are you? 🙄" I replied that it was a bit weird, but don't worry about it. He then replied "sorry about that 🙄". The conversaton ended and a few days later everything continued as normal. I figured that he probably just wanted to say something to me that evening but didn't really know what to say, so ended up saying something that wasn't actually funny.
A few days later, we were chatting on WhatsApp and he told me he had been doing a masters, I asked what in and he told me. I said I'd never heard of that and he replied "duh, everyone's heard of it". I assumed that was just his humour (because it was clearly a niche subject) and I continued chatting about other things.
Yesterday, I asked over WhatsApp about his masters and he was confused and asked who had told me that he had been doing postgraduate studies. I said that it was him who told me. He laughed and said he wasn't doing a masters and was probably drunk when he said it. I said that if I ever ask anything that's remotely serious, he deflects and talks nonsense but I can't tell when he's joking or telling the truth. After that he said he was drinking, didn't want to end up talking nonsense and so will talk to me another time.
I feel like I've offended him, but equally his jokes are weird and I don't know what to do with them.