NC-ing regular as this could out my workplace if anyone reads this who also works there! Sorry if it's long, don't want to drip feed.
I have a lovely colleague, let's call her Hannah, who is significantly overweight (this is relevant) and consequently has rather large breasts. She doesn't talk about her weight at work (and indeed why should she have to?) and so it would be fairly obvious that it's not a subject she wants to joke about. Same goes for the size of her breasts. Sorry, am trying to explain this sensitively and suspect I am failing.
Work Christmas party last night. At a public venue, so people we don't know were there. Not a huge place, so we probably made up about a third of the people there, and there were about 20 of us.
Two colleagues, one male one female (let's call them Tim and Jenny), started chatting and although I didn't hear the beginning of the conversation, the part I heard was initially about Jenny's breasts. Fine, her prerogative if she wishes to discuss that subject with Tim. The end of the conversation went something like this:
Jenny: mine are tiny!
Tim: yes, they're not exactly like Hannah's are they?
J: haha, I don't think so.
T: you could work on that!
J: I don't think there's any danger of me getting as big as Hannah any time soon.
T: her boobs you mean.
J: haha yes.
Then they both chuckled to themselves, clearly finding the breast jokes and weight reference funny.
Uncomfortable anyway, but Hannah overheard the whole bit about her. She stood there, while Tim and Jenny flustered over some faux-compliments about how 'spectacular' Hannah's breasts were because they were embarrassed at having been caught having the conversation by her. Hannah said something like 'can you leave my boobs out of this?' in a jokey way, but it was clear to see she was bothered by it. She sat quite quietly after that and the subject changed. Hannah looked upset, but no apology was forthcoming from Jenny or Tim.
So aibu? Cards on the table, I'm going to be really surprised if anyone thinks this is acceptable.