My initial situation is kinda similar to the one described here, but includes a troublesome third person.
I brought an acquaintance "Bob", who's also a good friend of my BFF, into my group of friends, with whom I share a hobby. Everybody including me befriended him really quick as he's a very nice person.
Anyways, a couple of months ago "John", started making jokes about how we would suit each other perfectly as a couple, that Bob might have a crush on me and sometimes he would even get really crude and pretend we already have a secret relationship going on including bed room speculations, which led to a lot of fun for everybody except me (usually Bob is not even present, if he is, he's just remaining silent). On multiple occasions I've made very clear that there's nothing going on, that I like being single (I really am). At one point I even asked, why he (and apparently others, who sometimes join the jokes) think anything could be going on between Bob an me. The answer was just "because you two are single", followed by childish laughter. I also tried joking and redirecting the topic to something else, or how I'd rather get together with John instead (he has a girlfriend of almost 10 years though, who I know very well). He liked the back joking, but quickly got back to "Bob + me". At least, when I don't answer at all, he stops after one or two extra remarks, which is what I've been doing recently.
Normally, I would just continue to ignore the jokes, since Bob has made no hints that he likes me more than the other girls or would be interested in something serious. I actually think he knows pretty well, that I'm not interested in him. The thing is, the occasional jokes have been going on almost a year by now with slightly higher frequency, and it's getting really annoying. At some point even my BFF (who initially introduced Bob to me, but is not in the group) asked me, if I could maybe imagine dating Bob. Apparently he is looking for a girlfriend. Another girl (who I suspect likes Bob) also asked me, if I'm interested in him because she thinks "we would suit each other so well". With the girls it was quick and easy to clarify my non-interest, they haven't asking anything else since then. Only John is still continuing.
All the jokes and hints are slowly making me paranoid, because I start looking for subtle hints (I think Bob is not the type to ask directly), I get more concious of how I talk to him (so I don't accidentally send mixed signals or something) etc. It's making me distance myself from Bob for no apparent reason (none he's at fault for at least) and I feel bad about that, since I consider him my friend, too.
So, my question is: How do I tell John to stop with the jokes, while maintaining my friendship to him and Bob? I also don't want to start some drama within the group, cause overall I like hanging out with them. Or should I just continue to ignore everything because "guys are just guys"? (If it's of any relevance the group consists of mainly 30-something men.)
Up till now I have been avoiding to say "There will never be something going on because I'm not attracted to Bob" since it's like I'm rejecting him without him even asking. There has to be a better way?
I didn't expect things to get this big in such a short time, I even felt a little silly at the beginning. But I thank you guys a million for understanding and giving me some insights as to possible reasons why "John" is behaving like this and furthermore for many possible solutions on how to deal with this. I would mark multiple answers as a solution if I could.
I've decided to directly confront him in private next time, to tell him the jokes are not funny and that I want him to stop and then see where this will go as suggested first by @Chris Sunami. "John" is actually not that bad of a person as he might look here right now. So I hope he'll understand and stop. Usually we get along really fine, except when he starts aforementioned jokes. If he doesn't, I probably will just ignore him and not meet with the group for awhile (or meet with the other when John's not coming along).
And yes, even though most people in the group are 30-something, they're rather childish. I didn't expect that thing would continue for so long. I wouldn't have minded one or two comments. Also, I want to stress that this is a private social group (not work) and most of the time I consider them to be my friends (yes, even "John"...). The group is also not rude in general, most of them don't say anything when this happens (can't tell if they are entertained or just don't want to be involved). The worse situation was when three of them "were having fun" (I just left on that day).
About his crude remarks, explicit sexual remarks have been - thankfully - rare so far, even if in two cases they definitely crossed lines. I thought it's a common thing among guys when there's a high number of them, which is why I didn't do/say much at the beginning. When there's more girls than guys, we never "joke" like that (even if it's all girls). (I actually get less harrassed than other guys, but more than other girls - which doesn't make it much better, but well...)