Why do guys make jokes about me and my husband's unborn baby being theirs?

Me and my husband are pregnant and I have now had 3 guy friends make comments to me about my baby being theirs. I’ve been with my husband a couple years now and it is mutual friends of ours saying this and its so bizarre to me. One guy said I’d love it if that baby were mine and when I said that it made me uncomfortable, he immediately apologized and said he was just joking but he’s avoided me since I told him I didnt like that. Which who cares but its awkward now.
One guy said it in person (in front of his wife and my husband) that’s my baby in you and I acted like I didn’t hear it cause it was so weird but his wife did and looked upset. (obviously)
And the third guy has told me and my husband that my baby is his or refers to my baby as “our child” when talking.
I literally don’t know how to respond and I feel so weird but I’m thinking I just need to correct the other 2 like I did the first. It’s so weird, no I don’t cheat on my husband. And I’m honestly wondering if anyone else has had their guy friends say stuff like this to you when you were pregnant. Idk what to do. Is it a joke? but some of the guys have made these comments like twice or three times now. What does this mean? At first I thought this wasn’t a thing to say to happily married people but three different guys have done it so I’m not sure.